Pixel and display device including the same

ABSTRACT

A pixel of display device includes a light emitting element, a first transistor coupled between first power source and a second node and having a gate electrode connected to a first node N 1 , and the first transistor being configured to control a driving current supplied to the light emitting element in response to a voltage of the first node, a first capacitor including one electrode connected to the first node and another electrode connected to a third node, a second transistor coupled between the third node and a data line, a third transistor coupled between the first node and the second node, a fourth transistor coupled between the first node and an initialization power source, a fifth transistor coupled between a reference power source and the third node, and an eighth transistor coupled between a fourth node and an anode initialization power source.

CROSS REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. patent application Ser. No.17/886,393, filed Aug. 11, 2022, which claims priority from and thebenefit of Korean Patent Application No. 10-2021-0158908, filed on Nov.17, 2021, each of which is hereby incorporated by reference for allpurposes as if fully set forth herein.

BACKGROUND Field

Embodiments of the invention relate generally to a display device, andmore specifically, a pixel capable of being driven at various drivingfrequencies and a display device including the same.

Discussion of the Background

With development of information technology, the importance of a displaydevice, which is a connection medium between a user and information, hasbeen increased.

The display device includes a plurality of pixels. Each of the pixelsincludes a plurality of transistors, and a light emitting element and acapacitor electrically connected to the transistors. The transistors arerespectively turned on in response to signals provided through a line,and thus a predetermined driving current is generated. The lightemitting element emits light in response to such a driving current.

Recently, in order to improve driving efficiency and minimize powerconsumption of the display device, a method of driving the displaydevice at a low frequency is used.

The above information disclosed in this Background section is only forunderstanding of the background of the inventive concepts, and,therefore, it may contain information that does not constitute priorart.

SUMMARY

Applicant recognized that the need for a pixel structure and a method ofdriving the pixels in a display device that is capable of improvingdisplay quality when a user requests driving the display device at a lowfrequency. For example, in a low-frequency driving mode in which alength of one frame period is increased, the hysteresis difference dueto a grayscale difference between adjacent pixels may be severe.Therefore, the difference of threshold voltage shift amounts of drivingtransistors of adjacent pixels may occur, and thus a screen drag (aghost phenomenon) may be recognized by a user.

Pixels constructed according to the principles and illustrativeembodiments of the invention are capable of being driven at variousdriving frequencies.

Further, display devices including the pixels constructed according tothe principles and illustrative embodiments of the invention are capableof more effectively improving the hysteresis characteristics (differencein a threshold voltage shift) by applying a bias with a substantiallyconstant voltage to a source electrode of a driving transistor to matchthe driving current direction and bias direction, thereby reducing orpreventing a light emitting element from unintentionally emitting lightwhen a driving transistor is initialized by separately supplying each ofan initialization voltage of a gate electrode of the driving transistorand an initialization voltage of an anode of the light emitting element.Thus, screen drag due to the hysteresis deviation may be reduced orremoved.

Additional features of the inventive concepts will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by practice of the inventive concepts.

According to one aspect of the invention, a pixel of a display deviceincludes a light emitting element, a first transistor coupled between afirst power source and a second node and having a gate electrodeconnected to a first node, and the first transistor being configured tocontrol a driving current supplied to the light emitting element inresponse to a voltage of the first node, a first capacitor including oneelectrode connected to the first node and another electrode connected toa third node, a second transistor coupled between the third node and adata line, a third transistor coupled between the first node and thesecond node, a fourth transistor coupled between the first node and aninitialization power source, a fifth transistor coupled between areference power source and the third node, and an eighth transistorcoupled between a fourth node and an anode initialization power source.

The pixel may further include a sixth transistor coupled between thefirst power source and a fifth node connected to one electrode of thefirst transistor, and a seventh transistor coupled between the secondnode and the fourth node.

The pixel may further include a ninth transistor coupled between thefifth node and bias power source.

The pixel may further include a second capacitor including one electrodeconnected to the first power source and another electrode connected tothe third node.

The first power source and one electrode of the sixth transistor may beconnected by a bridge pattern, and the pixel may further include a(2_1)-th capacitor including one electrode connected to the bridgepattern and another electrode connected to the other electrode of thefirst capacitor.

The first capacitor may have a capacitance equal to a sum of acapacitance of the second capacitor and a capacitance of the (2_1)-thcapacitor.

The second transistor may include a (2_1)-th transistor and a (2_2)-thtransistor connected in series, and include a first shielding patternoverlapping a node between the (2_1)-th transistor and the (2_2)-thtransistor, and the first shielding pattern may be connected to theanode initialization power source.

The third transistor may include a (3_1)-th transistor and a (3_2)-thtransistor connected in series, and include a second shielding patternoverlapping a node between the (3_1)-th transistor and the (3_2)-thtransistor, and the third shielding pattern may be connected to thefirst power source.

The fourth transistor may include a (4_1)-th transistor and a (4_2)-thtransistor connected in series, and include a third shielding patternoverlapping a node between the (4_1)-th transistor and the (4_2)-thtransistor, and the third shielding pattern may be connected to thefirst power source.

The fifth transistor may include a (5_1)-th transistor and a (5_2)-thtransistor connected in series, and include a third shielding patternoverlapping a node between the (5_1)-th transistor and the (5_2)-thtransistor, and the second shielding pattern may be connected to theanode initialization power source.

The pixel may further include at least one power supply to supply one ormore of the first power source, the initialization power source, thereference power source, and the anode initialization power source.

According to another aspect of the invention, a display device includesa substrate, a semiconductor layer disposed on the substrate and forminga channel region of a plurality of transistors, a first conductive layerdisposed on the semiconductor layer and forming a gate electrode of thetransistors and one electrode of capacitors; and a second conductivelayer disposed on the first conductive layer and forming anotherelectrodes of the capacitors and a plurality of shielding patterns. Theplurality of transistors includes a first transistor coupled betweenfirst power source and a second node and having a gate electrodeconnected to a first node, and the first transistor being configured tocontrol a driving current supplied to a light emitting element inresponse to a voltage of the first node, a second transistor coupledbetween a third node and a data line, a third transistor coupled betweenthe first node and the second node, a fourth transistor coupled betweenthe first node and an initialization power source, a fifth transistorcoupled between a reference power source and the third node, and aneighth transistor coupled between a fourth node and an anodeinitialization power source.

The semiconductor layer may include a first semiconductor pattern havinga first dummy portion extending in a first direction and connected tothe reference power source, and a second semiconductor pattern having asecond dummy portion separated from the first dummy portion, extendingin the first direction and connected to the anode initialization powersource.

The first semiconductor pattern may further include a first stem portionintegrally formed with the first dummy pattern, the first stem portionincluding a second sub-semiconductor pattern forming a channel of thesecond transistor, and a fifth sub-semiconductor pattern forming achannel of the fifth transistor.

The first dummy portion, the first stem portion, the secondsub-semiconductor pattern, and the fifth sub-semiconductor pattern maybe integrally formed.

Each of the second sub-semiconductor pattern and the fifthsub-semiconductor pattern may include a bent portion for forming a dualgate, and a first distance of the bent portion of the secondsub-semiconductor pattern in the first direction may be greater than asecond distance of the bent portion of the fifth sub-semiconductorpattern in the first direction.

The bent portion of the fifth sub-semiconductor pattern may furtherinclude an expansion portion protruding in the first direction on oneside of the bent portion.

The shielding patterns may include a first shielding pattern overlappingthe second sub-semiconductor pattern in a third direction, and a secondshielding pattern overlapping the fifth sub-semiconductor pattern in thethird direction.

The plurality of transistors may include a sixth transistor coupledbetween the first power source and a fifth node connected to oneelectrode of the first transistor, and a seventh transistor coupledbetween the second node and the fourth node.

The capacitors may include a first capacitor including one electrodeconnected to the first node and another electrode connected to the thirdnode, and a second capacitor including one electrode connected to thefirst power source and another electrode connected to the third node.

The display device may further include a third conductive layer disposedon the second conductive layer and forming a plurality of scan lines, aplurality of emission control lines, and a plurality of bridge patterns,and the first power source may be connected by one electrode of thesixth transistor and a third bridge pattern among the bridge patterns.

The third bridge pattern may include a horizontal portion extending in afirst direction, and first and second vertical portions disposed at bothends of the horizontal portion and extending in a second directioncrossing the first direction.

The capacitors may further include a (2_1)-th capacitor including oneelectrode connected to the horizontal portion and another electrodeconnected to the other electrode of the first capacitor.

The first vertical portion and the second vertical portion may be spacedapart from the other electrode of the first capacitor by a presetdistance.

The display device may further include a fourth conductive layerdisposed on the third conductive layer and having a plurality of datalines.

Each of the first vertical portion and the second vertical portion maybe disposed between the data lines and the other electrode of the firstcapacitor.

The display device may further include at least one power supply tosupply one or more of the first power source, the initialization powersource, the reference power source, and the anode initialization powersource.

According to yet another aspect of the invention, a pixel of a displaydevice includes a light emitting element, a first transistor coupledbetween a first voltage and a second node and having a gate electrodeconnected to a first node, a first capacitor including one electrodeconnected to the first node and another electrode connected to a thirdnode, a second transistor coupled between the third node and a dataline, a third transistor coupled between the first node and the secondnode, a fifth transistor coupled between a second voltage and the thirdnode, and an eighth transistor coupled between a fourth node and a thirdvoltage.

The pixel may further include a fourth transistor coupled between thefirst node and a fourth voltage.

The pixel may further include a sixth transistor coupled between thefirst voltage and a fifth node connected to one electrode of the firsttransistor, and a seventh transistor coupled between the second node andthe fourth node.

The pixel may further include a ninth transistor coupled between thefifth node and a fifth voltage.

The pixel may further include a second capacitor including one electrodeconnected to the first voltage and another electrode connected to thethird node.

The second transistor may have a gate electrode connected to a firstsignal.

The third transistor may have a gate electrode connected to a secondsignal.

The fourth transistor may have a gate electrode connected to a thirdsignal.

The fifth transistor may have a gate electrode connected to the secondsignal.

The sixth transistor may have a gate electrode connected to a fourthsignal.

The seventh transistor may have a gate electrode connected to a fifthsignal.

The eighth transistor may have a gate electrode connected to a sixthsignal.

The ninth transistor may have a gate electrode connected to the sixthsignal.

The first transistor may be configured to control a driving currentsupplied to the light emitting element in response to a voltage of thefirst node.

At least one of the first to ninth transistors may include an oxidesemiconductor.

The pixel may further include at least one power supply to supply one ormore of the first voltage, the second voltage, the third voltage and thefourth voltage.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention, andtogether with the description serve to explain the inventive concepts.

FIG. 1 is a block diagram of an embodiment of a display deviceconstructed according to the principles of the invention.

FIGS. 2A and 2B are equivalent circuit diagrams of embodiments of arepresentative pixel of the display device of FIG. 1

FIGS. 3A to 3F are timing diagrams of an embodiment of an operation ofthe pixel of FIG. 2A.

FIGS. 4A to 4D are timing diagrams of another embodiment of an operationof the pixel of FIG. 2A.

FIG. 5A is a conceptual diagram of an embodiment of a method of drivinga display device according to an image refresh rate.

FIG. 5B is a conceptual diagram illustrating of another embodiment of amethod of driving the display device according to the image refreshrate.

FIG. 6A is a schematic plan view of an embodiment of a plurality ofpixels constructed according to the principles of the invention based onthe pixel shown in FIG. 2A.

FIG. 6B is a plan view of an embodiment of a semiconductor layerincluded in the pixel of FIG. 6A.

FIG. 6C is a plan view of an embodiment of a first conductive layerincluded in the pixel of FIG. 6A.

FIG. 6D is a plan view of an embodiment of a second conductive layerincluded in the pixel of FIG. 6A.

FIG. 6E is a plan view of an embodiment of a third conductive layerincluded in the pixel of FIG. 6A.

FIG. 6F is a plan view of an embodiment of a fourth conductive layerincluded in the pixel of FIG. 6A.

FIG. 7 is a partial cross-sectional view of a portion of the pixels ofFIG. 6A.

FIGS. 8 to 10C are enlarged cross-sectional views of embodiments of anemission layer of a display device constructed according to theprinciples of the invention.

FIG. 11 is a schematic diagram of an embodiment of a two-stack tandememission structure of the emission layer constructed according to theprinciples of the invention.

DETAILED DESCRIPTION

In the following description, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of various embodiments or implementations of theinvention. As used herein “embodiments” and “implementations” areinterchangeable words that are non-limiting examples of devices ormethods employing one or more of the inventive concepts disclosedherein. It is apparent, however, that various embodiments may bepracticed without these specific details or with one or more equivalentarrangements. In other instances, well-known structures and devices areshown in block diagram form in order to avoid unnecessarily obscuringvarious embodiments. Further, various embodiments may be different, butdo not have to be exclusive. For example, specific shapes,configurations, and characteristics of an embodiment may be used orimplemented in another embodiment without departing from the inventiveconcepts.

Unless otherwise specified, the illustrated embodiments are to beunderstood as providing exemplary features of varying detail of someways in which the inventive concepts may be implemented in practice.Therefore, unless otherwise specified, the features, components,modules, layers, films, panels, regions, and/or aspects, etc.(hereinafter individually or collectively referred to as “elements”), ofthe various embodiments may be otherwise combined, separated,interchanged, and/or rearranged without departing from the inventiveconcepts.

The use of cross-hatching and/or shading in the accompanying drawings isgenerally provided to clarify boundaries between adjacent elements. Assuch, neither the presence nor the absence of cross-hatching or shadingconveys or indicates any preference or requirement for particularmaterials, material properties, dimensions, proportions, commonalitiesbetween illustrated elements, and/or any other characteristic,attribute, property, etc., of the elements, unless specified. Further,in the accompanying drawings, the size and relative sizes of elementsmay be exaggerated for clarity and/or descriptive purposes. When anembodiment may be implemented differently, a specific process order maybe performed differently from the described order. For example, twoconsecutively described processes may be performed substantially at thesame time or performed in an order opposite to the described order.Also, like reference numerals denote like elements.

When an element, such as a layer, is referred to as being “on,”“connected to,” or “coupled to” another element or layer, it may bedirectly on, connected to, or coupled to the other element or layer orintervening elements or layers may be present. When, however, an elementor layer is referred to as being “directly on,” “directly connected to,”or “directly coupled to” another element or layer, there are nointervening elements or layers present. To this end, the term“connected” may refer to physical, electrical, and/or fluid connection,with or without intervening elements. Further, the D1-axis, the D2-axis,and the D3-axis are not limited to three axes of a rectangularcoordinate system, such as the x, y, and z-axes, and may be interpretedin a broader sense. For example, the D1-axis, the D2-axis, and theD3-axis may be perpendicular to one another, or may represent differentdirections that are not perpendicular to one another. For the purposesof this disclosure, “at least one of X, Y, and Z” and “at least oneselected from the group consisting of X, Y, and Z” may be construed as Xonly, Y only, Z only, or any combination of two or more of X, Y, and Z,such as, for instance, XYZ, XYY, YZ, and ZZ. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

Although the terms “first,” “second,” etc. may be used herein todescribe various types of elements, these elements should not be limitedby these terms. These terms are used to distinguish one element fromanother element. Thus, a first element such as transistor discussedbelow could be termed a second element without departing from theteachings of the disclosure, and the claims are not necessarily limitedto the number of the element used in the specification.

Spatially relative terms, such as “beneath,” “below,” “under,” “lower,”“above,” “upper,” “over,” “higher,” “side” (e.g., as in “sidewall”), andthe like, may be used herein for descriptive purposes, and, thereby, todescribe one elements relationship to another element(s) as illustratedin the drawings. Spatially relative terms are intended to encompassdifferent orientations of an apparatus in use, operation, and/ormanufacture in addition to the orientation depicted in the drawings. Forexample, if the apparatus in the drawings is turned over, elementsdescribed as “below” or “beneath” other elements or features would thenbe oriented “above” the other elements or features. Thus, the exemplaryterm “below” can encompass both an orientation of above and below.Furthermore, the apparatus may be otherwise oriented (e.g., rotated 90degrees or at other orientations), and, as such, the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments and is not intended to be limiting. As used herein, thesingular forms, “a,” “an,” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. Moreover,the terms “comprises,” “comprising,” “includes,” and/or “including,”when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, components, and/orgroups thereof, but do not preclude the presence or addition of one ormore other features, integers, steps, operations, elements, components,and/or groups thereof. It is also noted that, as used herein, the terms“substantially,” “about,” and other similar terms, are used as terms ofapproximation and not as terms of degree, and, as such, are utilized toaccount for inherent deviations in measured, calculated, and/or providedvalues that would be recognized by one of ordinary skill in the art.

Various embodiments are described herein with reference to sectionaland/or exploded illustrations that are schematic illustrations ofidealized embodiments and/or intermediate structures. As such,variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, embodiments disclosed herein should not necessarily beconstrued as limited to the particular illustrated shapes of regions,but are to include deviations in shapes that result from, for instance,manufacturing. In this manner, regions illustrated in the drawings maybe schematic in nature and the shapes of these regions may not reflectactual shapes of regions of a device and, as such, are not necessarilyintended to be limiting.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure is a part. Terms,such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and should not be interpreted in anidealized or overly formal sense, unless expressly so defined herein.

FIG. 1 is a block diagram of an embodiment of a display deviceconstructed according to the principles to the invention.

Referring to FIG. 1 , the display device 1000 may include a displaypanel 100, scan drivers 200, 300, 400, and 500, emission drivers 600 and700, a data driver 800, and a timing controller 900.

The scan drivers 200, 300, 400, and 500 have been divided into a firstscan driver 200, a second scan driver 300, a third scan driver 400, anda fourth scan driver 500, which may be independently operable. Theemission drivers 600 and 700 have been divided into a first emissiondriver 600 and a second emission driver 700, which may be independentlyoperable. However, the division of the scan driver and the emissiondriver is for convenience of description, and at least a portion of thescan drivers and the emission drivers may be integrated into one drivingcircuit, module, and the like according to the particular desireddesign.

In an embodiment, the display device 1000 may further include a powersupply, which is not shown, to supply voltages for a first power sourceVDD, a second power source VSS, a third power source VREF (or referencepower source), a fourth power source Vint (or initialization powersource), a fifth power source Vaint (or anode initialization powersource), and a sixth power source Vbs (or bias power source) to thedisplay panel 100. The power supply may supply low power and high powerto define a gate-on level and a gate-off level of a scan signal, acontrol signal, and/or an emission control signal to the scan drivers200, 300, 400, and 500 and/or to the emission drivers 600 and 700. Thelow power source may have a voltage level lower than that of the highpower source. However, this is an example, and at least one of the firstpower source VDD, the second power source VSS, the third power sourceVREF (or the reference power source), the fourth power source Vint (orthe initialization power source), the fifth power source Vaint (or theanode initialization power source), the sixth power source Vbs (or thebias power source), the low power source, and the high power source maybe supplied from the timing controller 900 or the data driver 800.

The first power source VDD and the second power source VSS may generatevoltages for driving a light emitting element. In an embodiment, thevoltage level of the second power source VSS may be lower than a voltagelevel of the first power source VDD. For example, the voltage of thefirst power source VDD may be a positive voltage, and the voltage of thesecond power source VSS may be a negative voltage.

The reference power source VREF may be a power source for initializing apixel PX. For example, a capacitor and/or a transistor included in thepixel PX may be initialized by the voltage of the reference power sourceVREF. The reference power source VREF may be a positive voltage.

The initialization power source Vint may be a power source forinitializing the pixel PX. For example, a driving transistor included inthe pixel PX may be initialized by the voltage of the initializationpower source Vint. The initialization power source Vint may be anegative voltage.

The anode initialization power source Vaint may be a power source forinitializing the pixel PX. For example, an anode of the light emittingelement included in the pixel PX may be initialized by the voltage ofthe anode initialization power source Vaint. The anode initializationpower source Vaint may be a negative voltage.

The bias power source Vbs may be a power source for supplying apredetermined on-bias voltage to a source electrode of the drivingtransistor included in the pixel PX. The bias power source Vbs may be apositive voltage. In an embodiment, the voltage of the bias power sourceVbs may be a level similar to a data voltage of a black grayscale. Forexample, the voltage of the bias power source Vbs may be about 5 to 7V.

The display device 1000 may display an image at various image refreshrates (drive frequencies, or screen refresh rates) according to theparticular driving condition. The image refresh rate is a frequency atwhich a data signal is substantially written to the driving transistorof the pixel PX. For example, the image refresh rate is also referred toas a screen scan rate or a screen refresh frequency, and indicates thefrequency at which a display screen is refreshed for one second.

In an embodiment, an output frequency of the data driver 800 for onehorizontal line (or pixel row) and/or an output frequency of the firstscan driver 200 outputting a write scan signal may be determined inresponse to the image refresh rate. For example, a refresh rate fordriving a moving image may be a frequency of about 60 Hz or more (forexample, 120 Hz).

In an embodiment, the display device 1000 may adjust an output frequencyof the scan drivers 200, 300, 400, and 500 for one horizontal line (orpixel row) and an output frequency of the data driver 800 correspondingthereto according to the particular driving condition. For example, thedisplay device 1000 may display an image in response to various imagerefresh rates ranging from 1 Hz to 120 Hz. However, this is an example,and the display device 1000 may display an image also at an imagerefresh rate of 120 Hz or higher (for example, 240 Hz or 480 Hz).

The display panel 100 may include pixels PX respectively connected todata lines DL, scan lines SL1, SL2, SL3, and SL4, and emission controllines EL1 and EL2. The pixels PX may receive the voltages of the firstpower source VDD, the second power source VSS, the initialization powersource Vint, and the reference power source VREF from one or more powersources disposed outside the panel. In an embodiment, a pixel PXdisposed in an i-th row and a j-th column (where i and j are naturalnumbers) may be connected to scan lines SL1 i, SL2 i, SL3 i, and SL4 icorresponding to an i-th pixel row, emission control lines Eli and EL2 icorresponding to the i-th pixel row, and a data line DLj correspondingto a j-th pixel column.

In an embodiment, the signal lines SL1, SL2, SL3, SL4, EL1, EL2, and DLconnected to the pixel PX may be variously set in response to thecircuit structure of the pixel PX.

The timing controller 900 may generate a first driving control signalSCS1, a second driving control signal SCS2, a third driving controlsignal SCS3, a fourth driving control signal SCS4, a fifth drivingcontrol signal ECS1, a sixth driving control signal ECS2, and a seventhdriving control signal DCS in response to synchronization signalssupplied from outside of the panel. The first driving control signalSCS1 may be supplied to the first scan driver 200, the second drivingcontrol signal SCS2 may be supplied to the second scan driver 300, thethird driving control signal SCS3 may be supplied to the third scandriver 400, the fourth driving control signal SCS4 may be supplied tothe fourth scan driver 500, the fifth driving control signal ECS1 may besupplied to the first emission driver 600, the sixth driving controlsignal ECS2 may be supplied to the second emission driver 700, and theseventh driving control signal DCS may be supplied to the data driver800. In addition, the timing controller 900 may rearrange input imagedata supplied from outside of the panel into image data RGB and supplythe image data RGB to the data driver 800.

The first driving control signal SCS1 may include a first scan startpulse and clock signals. The first scan start pulse may control a firsttiming of a scan signal output from the first scan driver 200. The clocksignals may be used to shift the first scan start pulse.

The second driving control signal SCS2 may include a second scan startpulse and clock signals. The second scan start pulse may control a firsttiming of a scan signal output from the second scan driver 300. Theclock signals may be used to shift the second scan start pulse.

The third driving control signal SCS3 may include a third scan startpulse and clock signals. The third scan start pulse may control a firsttiming of a scan signal output from the third scan driver 400. The clocksignals may be used to shift the third scan start pulse.

The fourth driving control signal SCS4 may include a fourth scan startpulse and clock signals. The fourth scan start pulse may control a firsttiming of a scan signal output from the fourth scan driver 500. Theclock signals may be used to shift the fourth scan start pulse.

The fifth driving control signal ECS1 may include a first emissioncontrol start pulse and clock signals. The first emission control startpulse may control a first timing of an emission control signal outputfrom the first emission driver 600. The clock signals may be used toshift the first emission control start pulse.

The sixth driving control signal ECS2 may include a second emissioncontrol start pulse and clock signals. The second emission control startpulse may control a first timing of an emission control signal outputfrom the second emission driver 700. The clock signals may be used toshift the second emission control start pulse.

The seventh driving control signal DCS may include a source start pulseand clock signals. The source start pulse may control a sampling starttime point of data. The clock signals may be used to control a samplingoperation.

The first scan driver 200 may receive the first driving control signalSCS1 from the timing controller 900, and supply the scan signal (forexample, a first scan signal) to first scan lines SL1 based on the firstdriving control signal SCS1. For example, the first scan driver 200 maysequentially supply the first scan signal to the first scan lines SL1.When the first scan signal is sequentially supplied, the pixels PX maybe selected in a horizontal line unit (or a pixel row unit), and a datasignal may be supplied to the pixels PX. That is, the first scan signalmay be a signal used for data writing.

The first scan signal may be set to a gate-on level (for example, a lowvoltage). A transistor included in the pixel PX and receiving the firstscan signal may be set to a turn-on state when the first scan signal issupplied.

In an embodiment, in response to one scan line (for example, the firstscan line SL1 i) among the first scan lines SL1, the first scan driver200 may supply the scan signal (for example, the first scan signal) tothe first scan line SL1 i at the same frequency (for example, a secondfrequency) as the image refresh rate of the display device 1000. Thesecond frequency may be set as a portion of a first frequency fordriving the emission drivers 600 and 700.

The first scan driver 200 may supply the scan signal to the first scanlines SL1 in a display scan period of one frame. For example, the firstscan driver 200 may supply at least one scan signal to each of the firstscan lines SL1 during the display scan period.

The second scan driver 300 may receive the second driving control signalSCS2 from the timing controller 800, and supply the scan signal (forexample, a second scan signal) to second scan lines SL2 based on thesecond driving control signal SCS2. For example, the second scan driver300 may sequentially supply the second scan signal to the second scanlines SL2. The second scan signal may be supplied to initialize thetransistor and the capacitor included in the pixels PX and/or compensatefor a threshold voltage (Vth). When the second scan signal is supplied,the pixels PX may perform threshold voltage compensation and/orinitialization operations. The second scan signal may be set to agate-on level (for example, a low voltage). A transistor included in thepixel PX and receiving the second scan signal may be set to a turn-onstate when the second scan signal is supplied.

In an embodiment, in response to one scan line (for example, the secondscan line SL2 i) among the second scan lines SL2, the second scan driver300 may supply the scan signal (for example, the second scan signal) tothe second scan line SL2 i at the same frequency (for example, thesecond frequency) as an output of the first scan driver 200.

The second scan driver 300 may supply the scan signal to the second scanlines SL2 during the display scan period of one frame. For example, thesecond scan driver 300 may supply at least one scan signal to each ofthe second scan lines SL2 during the display scan period.

The third scan driver 400 may receive the third driving control signalSCS3 from the timing controller 900, and supply a scan signal (forexample, a third scan signal) to third scan lines SL3 based on the thirddriving control signal SCS3. For example, the third scan driver 400 maysequentially supply the third scan signal to the third scan lines SL3.The third scan signal may be supplied for initialization of the drivingtransistor included in the pixels PX and/or initialization the capacitorincluded in the pixels PX. When the third scan signal is supplied, thepixels PX may perform an initialization operation of the drivingtransistor and/or an initialization operation of the capacitor.

The third scan signal may be set to a gate-on level (for example, a lowvoltage). A transistor included in the pixel PX and receiving the thirdscan signal may be set to a turn-on state when the third scan signal issupplied.

In an embodiment, in response to one scan line (for example, the thirdscan line SL3 i) among the third scan lines SL3, the third scan driver400 may supply the scan signal (for example, the third scan signal) tothe third scan line SL3 i at the same frequency (for example, the secondfrequency) as the output of the first scan driver 200.

The fourth scan driver 500 may receive the fourth driving control signalSCS4 from the timing controller 900, and supply the scan signal (forexample, a fourth scan signal) to the fourth scan lines SL4 based on thefourth driving control signal SCS4. For example, the fourth scan driver500 may sequentially supply the fourth scan signal to the fourth scanlines SL4. The fourth scan signal may be supplied to initialize thelight emitting element included in the pixels PX and supply apredetermined bias voltage (for example, an on-bias voltage) to a sourceelectrode of the driving transistor included in the pixels PX. When thefourth scan signal supplied, the pixels PX may initialize the lightemitting element and supply the bias voltage.

The fourth scan signal may be set to a gate-on level (for example, a lowvoltage). A transistor included in the pixel PX and receiving the fourthscan signal may be set to a turn-on state when the fourth scan signal issupplied.

In an embodiment, in response to one scan line (for example, the fourthscan line SL4 i) among the fourth scan lines SL4, the scan driver 500may supply a scan signal (for example, a fourth scan signal) at thefirst frequency. Therefore, within one frame period, the scan signalsupplied to each of the fourth scan lines SL4 may be repeatedly suppliedevery predetermined period.

Accordingly, when the image refresh rate is reduced, the number ofrepetitions of an operation of supplying the fourth scan signal withinone frame period may be increased.

The first emission driver 600 may receive the fifth driving controlsignal ECS1 from the timing controller 900, and supply the emissioncontrol signal (for example, a first emission control signal) to thefirst emission control lines EL1 based on the fifth driving controlsignal ECS1. For example, the first emission driver 600 may sequentiallysupply the first emission control signal to the first emission controllines ELL

The second emission driver 700 may receive the sixth driving controlsignal ECS2 from the timing controller 900, and supply the emissioncontrol signal (for example, a second emission control signal) to thesecond emission control lines EL2 based on the sixth driving controlsignal ECS2. For example, the second emission driver 700 maysequentially supply the second emission control signal to the secondemission control lines EL2.

When the first emission control signal and/or the second emissioncontrol signal are/is supplied, the pixels PX may not emit light in thehorizontal line unit (or the pixel row unit). To this end, the firstemission control signal and the second emission control signal may beset to a gate-off level (for example, a high voltage) so that thetransistors included in the pixels PX are turned off. The transistorincluded in the pixel PX and receiving the first emission control signaland/or the second emission control signal may be turned off when thefirst emission control signal and/or the second emission control signalare/is supplied, and may be turned on in other cases.

The first emission control signal and the second emission control signalmay be used to control an emission time of the pixels PX. To this end,the first emission control signal and the second emission control signalmay be set to have a width wider than that of the scan signal.

In an embodiment, the first emission control signal and/or the secondemission control signal may have a plurality of gate-off level (forexample, high voltage) periods during one frame period. For example, thefirst emission control signal and/or the second emission control signalmay include a plurality of gate-on periods and a plurality of gate-offperiods for initialization, threshold voltage compensation, and thelike.

In an embodiment, similarly to the fourth scan driver 500, in responseto one emission control line (for example, a first emission control lineEL1 i) among the first emission control lines EL1 and one emissioncontrol line (for example, a second emission control line EL2 i) amongthe second emission control lines EL2, the first and second emissiondrivers 600 and 700 may supply an emission control signal (for example,first and second emission control signals) to the first and secondemission control lines EL1 i and EL2 i at the first frequency.Therefore, within one frame period, the emission control signalsrespectively supplied to the first and second emission control lines EL1and EL2 may be repeatedly supplied every predetermined period.

Accordingly, when the image refresh rate is reduced, the number ofrepetitions of an operation of supplying the first and emission controlsignals within one frame period may be increased.

The data driver 800 may receive the seventh driving control signal DCSand the image data RGB from the timing controller 900. The data driver800 may supply the data signal to the data lines DL in response to theseventh driving control signal DCS. The data signal supplied to the datalines DL may be supplied to the pixels PX selected by the scan signal(for example, the first scan signal). To this end, the data driver 800may supply the data signal to the data lines DL to be synchronized withthe scan signal.

In an embodiment, the data driver 800 may supply the data signal to thedata lines DL during one frame period in response to the image refreshrate. For example, the data driver 800 may supply the data signal to besynchronized with the scan signal supplied to the first scan lines SL1.

FIGS. 2A and 2B are equivalent circuit diagrams of embodiments of arepresentative pixel of the display device of FIG. 1 In FIGS. 2A and 2B,the pixel PX positioned in an i-th horizontal line (or the i-th pixelrow) and connected to the j-th data line DLj is shown for convenience ofdescription.

Referring to FIG. 2A, the pixel PX may include a light emitting elementLD, first to ninth transistors T1 to T9, a first capacitor C1, and asecond capacitor C2.

A first electrode of the light emitting element LD may be connected to asecond electrode (for example, a drain electrode) of the firsttransistor T1 (or a second node N2) via the sixth transistor T6, and asecond electrode of the light emitting element LD may be connected tothe second power source VSS. Specifically, the first electrode of thelight emitting element LD may be electrically connected to the secondelectrode of the first transistor T1 via a fourth node N4 to which oneelectrode of the sixth transistor T6 and one electrode of the seventhtransistor T7 are commonly connected.

The first transistor T1 may be connected to the first power source VDDvia the ninth transistor T9, and may be connected to the first electrodeof the light emitting element LD via the sixth transistor T6. The firsttransistor T1 may generate a driving current and provide the drivingcurrent to the light emitting element LD. A gate electrode of the firsttransistor T1 may be connected to the first node N1. The firsttransistor T1 may function as the driving transistor of the pixel PX.The first transistor T1 may control an amount of current flowing fromthe first power source VDD to the second power source VSS via the lightemitting element LD in response to a voltage applied to the first nodeN1.

The first capacitor C1 may be connected between the first node N1 and athird node N3 corresponding to the gate electrode of the firsttransistor T1. The first capacitor C1 may store a voltage correspondingto a voltage difference between the first node N1 and the third node N3.

The second capacitor C2 may be connected between the first power sourceVDD and the third node N3. The second capacitor C2 may store a voltagecorresponding to a voltage difference between the first power source VDDand the third node N3. As one electrode of the second capacitor C2 isconnected to the first power source VDD, which is a substantiallyconstant voltage source, and another electrode is connected to the thirdnode N3, the second capacitor C2 may maintain a data signal (or a datavoltage) written to the third node N3 through the second transistor T2in the display scan period during a self-scan period in which the datasignal is not written. That is, the second capacitor C2 may stabilizethe voltage of the third node N3.

The second transistor T2 may be connected between the data line DLj andthe third node N3. The second transistor T2 may include a gate electrodereceiving the scan signal. For example, the gate electrode of the secondtransistor T2 may be connected to the first scan line SL1 i to receivethe first scan signal. The second transistor T2 may be turned on whenthe first scan signal is supplied to the first scan line SL1 i, toelectrically connect the data line DLj and the third node N3.Accordingly, the data signal (or the data voltage) may be transferred tothe third node N3.

The third transistor T3 may be connected to the first node N1corresponding to the gate electrode of the first transistor T1 and thesecond node N2 (or a second electrode or a drain electrode of the firsttransistor T1). The third transistor T3 may include a gate electrodereceiving the scan signal. For example, the gate electrode of the thirdtransistor T3 may be connected to the second scan line SL2 i to receivethe second scan signal. The third transistor T3 may be turned on whenthe second scan signal is supplied to the second scan line SL2 i, toelectrically connect the first node N1 and the second node N2. By theturn-on of the third transistor T3, the first transistor T1 may have adiode connection shape. When the first transistor T1 has the diodeconnection shape, a threshold voltage of the first transistor T1 may becompensated.

The fourth transistor T4 may be connected between the initializationpower source Vint and the first node N1. The fourth transistor T4 mayinclude a gate electrode receiving the scan signal. For example, thegate electrode of the fourth transistor T4 may be connected to the thirdscan line SL3 i to receive the third scan signal. The fourth transistorT4 may be turned on when the third scan signal is supplied to the thirdscan line SL3 i, to electrically connect the initialization power sourceVint and the first node N1. Accordingly, the voltage of theinitialization power source Vint may be supplied to the first node N1.Therefore, a voltage of the first node N1 may be initialized to thevoltage of the initialization power source Vint.

The fifth transistor T5 may be connected between the reference powersource VREF and the third node N3. The fifth transistor T5 may include agate electrode receiving the scan signal. For example, the gateelectrode of the fifth transistor T5 may be connected to the second scanline SL2 i to receive the second scan signal. The fifth transistor T5may be turned on when the second scan signal is supplied to the secondscan line SL2 i, to electrically connect the reference power source VREFand the third node N3. Accordingly, the voltage of the reference powersource VREF may be supplied to the third node N3. Therefore, the voltageof the third node N3 may be initialized to the voltage of the referencepower source VREF.

Since the gate electrodes of the third and fifth transistors T3 and T5are connected to the same scan line (that is, the second scan line SL2i), the third and fifth transistors T3 and T5 may be turned off orturned on simultaneously.

The sixth transistor T6 may be connected between the first power sourceVDD and the first electrode of the first transistor T1 (or a fifth nodeN5). The sixth transistor T6 may include a gate electrode receiving theemission control signal. For example, the gate electrode of the sixthtransistor T6 may be connected to the first emission control line EL1 ito receive first the emission control signal. The sixth transistor T6may be turned off when the first emission control signal is supplied tothe first emission control line EL1 i, and may be turned on in othercases. The sixth transistor T6 of the turn-on state may connect thefirst electrode of the first transistor T1 to the first power sourceVDD.

The seventh transistor T7 may be connected between the second node N2corresponding to the second electrode of the first transistor T1 and theanode of the light emitting element LD (or a fourth node N4). Theseventh transistor T7 may include a gate electrode receiving theemission control signal. For example, the gate electrode of the seventhtransistor T7 may be connected to the second emission control line EL2 ito receive the second emission control signal. The seventh transistor T7may be turned off when the second emission control signal is supplied tothe second emission control line EL2 i, and may be turned on in othercases. The seventh transistor T7 of the turn-on state may electricallyconnect the second node N2 and the fourth node N4.

When both of the sixth and seventh transistors T6 and T7 are turned on,the light emitting element LD may emit light with a luminancecorresponding to the voltage of the first node N1

In an embodiment, when the sixth transistor T6 is turned on and theseventh transistor T7 is turned off, threshold voltage compensation ofthe first transistor T1 may be performed.

The eighth transistor T8 may be connected between the light emittingelement LD (or the fourth node N4) and the anode initialization powersource Vaint. The eighth transistor T8 may include a gate electrodereceiving the scan signal. For example, the gate electrode of the eighthtransistor T8 may be connected to the fourth scan line SL4 i to receivethe fourth scan signal. The eighth transistor T8 may be turned on whenthe fourth scan signal is supplied to the fourth scan line SL4 i, toelectrically connect the anode initialization power source Vaint and thefourth node N4. Accordingly, the voltage of the fourth node N4 (or theanode of the light emitting element LD) may be initialized to thevoltage of the anode initialization power source Vaint. When the voltageof the anode initialization power source Vaint is supplied to the anodeof the light emitting element LD, the parasitic capacitance of the lightemitting element LD may be discharged. As the residual voltagegenerating the parasitic capacitance is discharged (removed),unintentional fine emission may be reduced or prevented. Therefore, theblack expression ability of the pixel PX may be improved. Thus, byseparating the initialization operation of the gate electrode of thefirst transistor T1 (or the first node N1) and the initializationoperation of the anode of the light emitting element LD (or the fourthnode N4), the light emitting element LD may be prevented fromunintentionally emitting light during the initialization operation ofthe gate electrode of the first transistor T1 (or the first node N1).

The ninth transistor T9 may be connected between the first electrode ofthe first transistor T1 (or a fifth node N5) and the bias power sourceVbs. The ninth transistor T9 may include a gate electrode receiving thescan signal. For example, the gate electrode of the ninth transistor T9may be connected to the fourth scan line SL4 i to receive the fourthscan signal. The ninth transistor T9 may be turned on when the fourthscan signal is supplied to the fourth scan line SL4 i, to electricallyconnect the fifth node N5 and the bias power source Vbs.

As described with reference to FIG. 1 , the ninth transistor T9 maysupply a high voltage to the first electrode of the first transistor T1based on the bias power source Vbs having a positive voltage.Accordingly, the first transistor T1 may have an on-bias state.

A period in which the second transistor T2 is turned on and a period inwhich the third, fifth, and sixth transistors T3, T5, and T6 are turnedon may not overlap. For example, when the third, fifth, and sixthtransistors T3, T5, and T6 are turned on, the threshold voltagecompensation of the first transistor T1 may be performed, and when thesecond transistor T2 is turned on, the data writing may be performed.Therefore, the threshold voltage compensation period and the datawriting period may be separated from each other.

In a low-frequency driving mode in which a length of one frame period isincreased, the hysteresis difference due to a grayscale differencebetween adjacent pixels may be severe. Therefore, the difference ofthreshold voltage shift amounts of driving transistors of adjacentpixels may occur, and thus a screen drag (a ghost phenomenon) may berecognized by a user.

Display devices constructed according to the principles and illustrativeembodiments may periodically apply a bias with a substantially constantvoltage to a source electrode of the driving transistor (for example,the first transistor T1) using the ninth transistor T9. Therefore, thehysteresis deviation due to the grayscale difference between adjacentpixels may be removed, and thus screen drag due to the hysteresisdeviation may be reduced or removed.

A first pixel PX1 shown in FIG. 2B is different from the pixel PX shownin FIG. 2A in that the second transistor T2, the third transistor T3,the fourth transistor T4, and the fifth transistor T5 are formed as dualgates and the first pixel PX1 further includes a (2_1) capacitor, andthe remaining configurations and driving method are substantially thesame. Hereinafter, repetitive descriptions of like components oroperations are omitted to avoid redundancy, and the differences aremainly described.

The second transistor T2 may include a (2_1)-th transistor T2_1 and a(2_2)-th transistor T2_2 connected in series, and a first shieldingpattern (refer to SHP1 of FIGS. 6A and 6D) overlapping a node betweenthe (2_1) transistor T2_1 and the (2_2) transistor T2_2. The firstshielding pattern may be connected to the anode initialization powersource Vaint.

The third transistor T3 may include a (3_1)-th transistor T3_1 and a(3_2)-th transistor T3_2 connected in series, and a second shieldingpattern (refer to SHP2 of FIGS. 6A and 6D) overlapping a node betweenthe (3_1)-th transistor T3_1 and the (3_2)-th transistor T3_2. Thesecond shielding pattern may be connected to the anode initializationpower source Vaint.

The fourth transistor T4 may include a (4_1)-th transistor T4_1 and a(4_2)-th transistor T4_2 connected in series, and a third shieldingpattern (refer to SHP3 of FIGS. 6A and 6D) overlapping a node betweenthe (4_1)-th transistor T4_1 and the (4_2)-th transistor T4_2. The thirdshielding pattern may be connected to the first power source VDD.

The fifth transistor T5 may include a (5_1)-th transistor T5_1 and a(5_2)-th transistor T5_2 connected in series, and a third shieldingpattern (refer to SHP3 of FIGS. 6A and 6D) overlapping a node betweenthe (5_1)-th transistor T5_1 and the (5_2)-th transistor T5_2. The thirdshielding pattern may be connected to the first power source VDD.

The (2_1)-th capacitor C2-1 may include one electrode connected to abridge pattern (refer to BRP3 shown in FIG. 6A or BRP3_2 shown in FIG.6E) connecting the first power source VDD and the sixth transistor T6,and another electrode of the first capacitor C1 (or the third node N3).According to an embodiment, the capacitance of the first capacitor C1may be equal to a sum of a capacitance of the second capacitor C2 and acapacitance of the (2_1)-th capacitor C2_1. Accordingly, the ratio ofthe capacitance of the first capacitor C1 and the sum of the capacitanceof the second capacitor C2 and the (2_1)-th capacitor C2-1 may besubstantially constantly maintained at 1:1 regardless of the differencesin manufacturing processes. This is described later in detail withreference to FIGS. 6A to 6F.

FIGS. 3A to 3F are timing diagrams of an embodiment of an operation ofthe pixel of FIG. 2A.

First, referring to FIGS. 2A and 3A, the pixel PX may receive signalsfor image display during a display scan period DSP. The display scanperiod DSP may include a period in which a data signal DVj actuallycorresponding to an output image is written.

First and second emission control signals EM1 i and EM2 i may besupplied to the first and second emission control lines EL1 i and EL2 i,respectively, and first to fourth scan signals GWi, GCi, GIi, and EBimay be supplied to the first to fourth scan lines SL1 i, SL2 i, SL3 i,and SL4 i, respectively.

At a first time point t1, the third scan signal GIi may transmit from agate-off level to a gate-on level. Accordingly, the fourth transistor T4may be turned on. Accordingly, the voltage of the initialization powersource Vint may be supplied to the first node N1 (or the gate electrodeof the first transistor T1), and the first node N1 may be initialized tothe voltage of the initialization power source Vint.

In addition, the second scan signal GCi may transit from a gate-offlevel to a gate-on level. Accordingly, the third transistor T3 may beturned on. In addition, since the second emission control signal EM2 imaintains a gate-off level, the seventh transistor T7 may be turned offor may maintain a turn-off state. Accordingly, the voltage of theinitialization power source Vint supplied to the first node N1 may beprevented from being supplied to the fourth node N4, thereby preventingthe light emitting element LD from unintentionally emitting light.

In addition, the fifth transistor T5 may be turned on by the second scansignal GCi of the gate-on level. Accordingly, the voltage of thereference power source VREF may be supplied to the third node N3, andthus the third node N3 may be initialized to the voltage of thereference power source VREF.

Specifically, referring to FIG. 3B, during a first period P1 a from thefirst time point t1 to a second time point t2 shown in FIG. 3B, thevoltage of the initialization power source Vint may be supplied to thefirst node N1 and the voltage of the reference power source VREF may besupplied to the third node N3. That is, the first period P1 a may be aninitialization period (or a first initialization period) forinitializing the gate electrode of the driving transistor (the firsttransistor T1) and the third node N3.

Since the third scan signal GIi maintains the gate-on level during theperiod from the first time point t1 to the second time point t2, theinitialization period of the gate electrode of the first transistor T1(or the first node N1) may be performed during the corresponding period.In addition, since the second scan signal GCi maintains the gate-onlevel during a period from the first time point t1 to a sixth time pointt6, the voltage of the reference power source VREF may be supplied tothe third node N3 during the corresponding period.

At a third time point t3, the first emission control signal EM1 i maytransit from a gate-off level to a gate-on level. Accordingly, the sixthtransistor T6 may be turned on, and the first electrode (for example,the source electrode) of the first transistor T1 may be connected to thefirst power source VDD.

In addition, since the second scan signal GCi maintains the gate-onlevel, the third transistor T3 may maintain the turn-on state.Accordingly, the first transistor T1 may have a diode connection shape.In this case, the voltage corresponding to the difference (or thevoltage difference) between the voltage of the first power source VDDand the threshold voltage of the first transistor T1 may be sampled atthe first node N1.

Accordingly, during a second period P2 a from the third time point t3 toa fourth time point t4 shown in FIG. 3C, the first transistor T1 may bea diode connection shape, and thus the threshold voltage of the firsttransistor T1 may be compensated. That is, the second period P2 a may bea threshold voltage compensation period.

In the second period P2 a, the threshold voltage compensation may beperformed by the voltage of the first power source VDD, which is asubstantially constant voltage source. Therefore, a threshold voltagecompensation operation may be performed based on a fixed voltage ratherthan a data signal (data voltage) that may be variable according to apixel row and/or a frame.

At the fourth time point t4, the first emission control signal EM1 i maytransit from a gate-on level to a gate-off level. Accordingly, the sixthtransistor T6 may be turned off.

At a fifth time point t5, the second scan signal GCi may transit from agate-on level to a gate-off level. Accordingly, the third and fifthtransistors T3 and T5 may be turned off.

At the sixth time point t6, the first scan signal GWi may transit from agate-off level to a gate-on level, and thus the second transistor T2 maybe turned on. Accordingly, the data signal DVj may be supplied to thethird node N3.

Since the first node N1 is connected to the third node N3 by the firstcapacitor C1, a change amount of a voltage of the third node N3 (thatis, “DATA−VREF”) may be reflected to the first node N1. Therefore, thevoltage of the first node N1 may change to “VDD−Vth+(DATA−VREF)”. Here,DATA may be a voltage corresponding to the data signal DVj, VREF may bethe voltage of the reference power source VREF, VDD may be the voltageof the first power source VDD, and Vth may be the threshold voltage ofthe first transistor T1.

Accordingly, during a third period P3 a from the sixth time point t6 toa seventh time point t7 shown in FIG. 3D, the data signal DVj may bewritten to the pixel PX. That is, the third period P3 a may be a datawriting period.

In an embodiment, the length of the third period P3 a, that is, thelength (the pulse width) of the first scan signal GWi may be onehorizontal period (1H). However, the length of the first scan signal GWiis not limited thereto, and, for example, the length of the first scansignal GWi may be two or more horizontal periods 2H.

At the seventh time point t7, the first scan signal GWi may transit froma gate-on level to a gate-off level. Accordingly, the second transistorT2 may be turned off.

At an eighth time point t8, the fourth scan signal EBi may transit froma gate-off level to a gate-on level. Accordingly, the eighth transistorT8 may be turned on, and thus the voltage of the anode initializationpower source Vaint may be supplied to the fourth node N4. That is, anodeinitialization of the light emitting element LD may be performed in afourth period P4 a.

In addition, the ninth transistor T9 may be turned on, and thus thevoltage of the bias power source Vbs may be supplied to the fifth nodeN5 (or the source electrode of the first transistor T1). Therefore, thevoltage of the bias power source Vbs having a positive voltage may besupplied to the first electrode (or the source electrode) of the firsttransistor T1.

Accordingly, during the fourth period P4 a from the eighth time point t8to a ninth time point t9 shown in FIG. 3E, the on-bias may be applied tothe first transistor T1. That is, the fourth period P4 a may be anon-bias period (or a first on-bias period).

At the ninth time point t9, the fourth scan signal EBi may transit froma gate-on level to a gate-off level. Accordingly, the eighth transistorT8 and the ninth transistor T9 may be turned off.

The hysteresis characteristic (that is, the threshold voltage shift) ofthe first transistor T1 may be improved, by applying the on-bias to thefirst transistor T1 in the fourth period P4 a.

Therefore, the pixel PX and the display device 1000 of FIG. 1 accordingto an operation of FIG. 3A may remove or improve the hysteresischaracteristic while removing a threshold voltage deviation of the firsttransistor T1, and thus an image defect (flicker, color drag, aluminance decrease, or the like) may be improved. In particular, thehysteresis characteristic (the difference of the threshold voltageshift) may be more effectively improved, by applying a bias with asubstantially constant voltage to the source electrode of the firsttransistor T1 (or the driving transistor) to match a driving currentdirection and a bias direction.

Referring to FIG. 3F, at a tenth time point t10, the first and secondemission control signals EM1 i and EM2 i may transit from a gate-offlevel to a gate-on level. Accordingly, since the sixth and seventhtransistors T6 and T7 may be turned on, the pixel PX may emit light in afifth period P5 a after the tenth time point t10 shown in FIG. 3F. Thatis, the fifth period P5 a may be an emission period (or a first emissionperiod).

FIGS. 4A to 4D are timing diagrams of an embodiment of an operation ofthe pixel of FIG. 2A.

Referring to FIGS. 2A, 3A, and 4A, in order to maintain a luminance ofan image output in the display scan period DSP illustrated in FIGS. 3Ato 3F, an on-bias voltage may be applied to the first electrode of thefirst transistor T1 (for example, the source electrode or the fifth nodeN5) in a self-scan period SSP. For example, the self-scan period SSP maybe a period continuously following the display scan period DSP in aframe period.

According to an image frame rate, one frame may include at least oneself-scan period SSP. The self-scan period SSP may include an on-biasperiod (or a second on-bias period) of a sixth period P2 b an on-biasperiod (or a third on-bias period) of a seventh period P4 b, and anemission period (or a second emission period) of an eighth period P5 b.In addition, the operation of the self-scan period SSP of FIG. 4A issubstantially the same as or similar to the operation of the displayscan period DSP of FIG. 3A except for signal supply for theinitialization of the gate electrode of the first transistor T1 in thefirst period P1 a of FIG. 3B, signal supply for the threshold voltagecompensation in the second period P2 a (or the threshold voltagecompensation period) of FIG. 3C, and signal supply for the data signalwriting in the third period P3 a (or the data writing period) of FIG.3D.

In an embodiment, the scan signal is not supplied to the second to fifthtransistors T2, T3, T4, and T5 in the self-scan period SSP. For example,in the self-scan period SSP, the first scan signal GWi, the second scansignal GCi, and the third scan signal Gii respectively supplied to thefirst scan line SL1 i, the second scan line SL2 i, and the third scanline SL3 i may have a gate-off level (or a high level (H)). Accordingly,in the self-scan period SSP, the gate electrode initialization period(for example, the first period P1 a) of the first transistor T1, thethreshold voltage compensation period (for example, the second period P2a), and the data writing period (for example, the third period P3 a) arenot included.

Specifically, referring to FIG. 4 b , since the first emission controlsignal EM1 i of the gate-on level is supplied during the sixth period P2b (or the second on-bias period) from an eleventh time point t11 to atwelfth time point t12 shown in FIG. 4B, the sixth transistor T6 may beturned on or may maintain a turn-on state. Accordingly, the voltage ofthe first power source VDD of the high voltage may be supplied to thefirst electrode (or the source electrode) of the first transistor T1,and thus the first transistor T1 may have an on-bias state.

Since the fourth scan signal EBi of the gate-on level is supplied duringthe seventh period P4 b (or the third on-bias period) from a thirteenthtime point t13 to a fourteenth time point t14 shown in FIG. 4C, theninth transistor T9 may be turned on or may maintain a turn-on state.Since the ninth transistor T9 is turned on, the voltage of the biaspower source Vbs may be supplied to the fifth node N5 (or the sourceelectrode of the first transistor T1). Therefore, the voltage of thebias power source Vbs having the positive voltage may be supplied to thefirst electrode (or the source electrode) of the first transistor T1.

In addition, the eighth transistor T8 may be turned on. Accordingly, thevoltage of the anode initialization power source Vaint may be suppliedto the fourth node N4 (or the first electrode of the light emittingelement LD), and thus the fourth node N4 may be initialized to thevoltage of the anode initialization power source Vaint.

Since both of the first emission control signal EM1 i and the secondemission control signal EM2 i have the gate-on level in the eighthperiod P5 b (or the second emission period) after a fifteenth time pointt15 shown in FIG. 4D, the sixth and seventh transistors T6 and T7 may beturned on, and thus the pixel PX may emit light.

Here, the fourth scan signal EBi and the first and second emissioncontrol signals EM1 i and EM2 i may be supplied at the first frequencyregardless of the image refresh rate. Therefore, even in a case wherethe image refresh rate is changed, the initialization operation of thelight emitting element LD and the application of the on-bias in theon-bias period (the fourth period P4 a, the sixth period P2 b, and/orthe seventh period P4 b) may be periodically performed always.Therefore, flicker may be improved in response to various image refreshrates (particularly, low-frequency driving).

In the self-scan period SSP, the data driver 800 of FIG. 1 may notsupply the data signal to the pixel PX. Therefore, power consumption maybe further reduced.

FIG. 5A is a conceptual diagram of an embodiment of a method of drivingthe display device according to the image refresh rate, and FIG. 5B is aconceptual diagram of an embodiment of a method of driving the displaydevice according to the image refresh rate.

Referring to FIGS. 1 to 5A, the pixel PX may perform the operation ofFIGS. 3A to 3G in the display scan period DSP and perform the operationof FIGS. 4A to 4D in the self-scan period SSP.

In an embodiment, the output frequency of the first scan signal GWi andthe second scan signal GCi may vary according to an image refresh rateRR. For example, the first scan signal GWi and the second scan signalGCi may be output at the same frequency (second frequency) as the imagerefresh rate RR.

In an embodiment, regardless of the image refresh rate RR, the thirdscan signal GIi, the fourth scan signal EBi, the first emission controlsignal EM1 i, and the second emission control signal EM2 i may be outputat a substantially constant frequency (first frequency). For example, anoutput frequency of the third scan signal GIi, the fourth scan signalEBi, the first emission control signal EM1 i, and the second emissioncontrol signal EM2 i may be set to twice a maximum refresh rate of thedisplay device 1000.

In an embodiment, lengths of the display scan period DSP and theself-scan period SSP may be substantially the same. However, the numberof self-scan periods SSP included in one frame period may be determinedaccording to the image refresh rate RR.

As shown in FIG. 5A, when the display device 1000 is driven at an imagerefresh rate RR of 120 Hz, one frame period may include one display scanperiod DSP and one self-scan period SSP. Accordingly, when the displaydevice 1000 is driven at the image refresh rate RR of 120 Hz, each ofthe pixels PX may alternately repeat emission and non-emission twiceduring one frame period.

In addition, when the display device 1000 is driven at an image refreshrate RR of 80 Hz, one frame period may include one display scan periodDSP and two successive self-scan periods SSP. Accordingly, when thedisplay device 1000 is driven at the image refresh rate RR of 80 Hz,each of the pixels PX may alternately repeat emission and non-emissionthree times during one frame period.

In a method similar to that described above, the display device 1000 maybe driven at a driving frequency of 60 Hz, 48 Hz, 30 Hz, 24 Hz, 1 Hz, orthe like by adjusting the number of self-scan periods SSP included inone frame period. In other words, the display device 1000 may supportvarious image refresh rates RR with frequencies corresponding to analiquot of the first frequency.

In addition, as the driving frequency decreases, the number of self-scanperiods SSP increases, and thus on-bias and/or off-bias of apredetermined size may be periodically applied to each of the firsttransistors T1 included in each of the pixels PX. Therefore, luminancereduction, flicker, and screen drag in low-frequency driving may beimproved.

As shown in FIG. 5B, the display device 1000 may display an image usingdifferent start pulses FLM1 and FLM2 according to the image refresh rateRR. For example, when the display device 1000 is driven at an imagerefresh rate RR of 80 Hz, the display device 1000 may display an imageusing the first start pulse FLM1, and when the display device 1000 isdriven at an image refresh rate RR of 60 Hz, the display device 1000 maydisplay an image using the second start pulse FLM2. At this time, sincethe first scan driver 200 and the second scan driver 300 are driven atdifferent frequencies (or second frequencies) according to the imagerefresh rate RR, the first start pulse FLM1 and the second start pulseFLM2 may include a first scan start pulse and a second scan start pulsedifferent from each other.

FIG. 6A is a schematic plan view of an embodiment of a plurality ofpixels constructed according to the principles of the invention based onthe pixel shown in FIG. 2A. FIG. 6B is a plan view of an embodiment of asemiconductor layer included in the pixel of FIG. 6A. FIG. 6C is a planview of an embodiment of a first conductive layer included in the pixelof FIG. 6A. FIG. 6D is a plan view of an embodiment of a secondconductive layer included in the pixel of FIG. 6A. FIG. 6E is a planview of an embodiment of a third conductive layer included in the pixelof FIG. 6A. FIG. 6F is a plan view of an embodiment of a fourthconductive layer included in the pixel of FIG. 6A.

Referring to FIGS. 1, 2A, and 6A, the display panel 100 may include aneleventh pixel PX11 (or an eleventh pixel area PXA11), a twelfth pixelPX12 (or a twelfth pixel area PXA12), and a thirteenth pixel PX13 (or athirteenth pixel area PXA13). The eleventh pixel PX11, the twelfth pixelPX12, and the thirteenth pixel PX13 may define the configuration of oneunit pixel.

According to an embodiment, the eleventh to thirteenth pixels PX11 toPX13 may emit light in different colors. For example, the eleventh pixelPX11 may be a red pixel emitting red light, the twelfth pixel PX12 maybe a green pixel emitting green light, and the thirteenth pixel PX13 maybe a blue pixel emitting blue light. However, the color, type, number,and/or the like of the pixels defining the unit pixel are notparticularly limited, and, for example, the color of light emitted byeach of the pixels may be variously changed. According to an embodiment,the eleventh to thirteenth pixels PX11 to PX13 may emit light in thesubstantially the same color. For example, the eleventh to thirteenthpixels PX11 to PX13 may be blue pixels emitting blue light.

Since the eleventh to thirteenth pixels PX11 to PX13 (or pixel drivingcircuits of the eleventh to thirteenth pixels PX11 to PX13) aresubstantially the same or similar to each other, hereinafter, theeleventh pixel PX11 is described by encompassing the eleventh tothirteenth pixels PX11 to PX13.

The eleventh pixel PX11 may include a semiconductor layer ACT, a firstconductive layer GAT1, a second conductive layer GAT2, a thirdconductive layer SD1, and a fourth conductive layer SD2. Thesemiconductor layer ACT, the first conductive layer GAT1, the secondconductive layer GAT2, the third conductive layer SD1, and the fourthconductive layer SD2 may be formed on different layers through differentprocesses.

The semiconductor layer ACT may be an active layer forming a channel ofthe first to ninth transistors T1 to T9. The semiconductor layer ACT mayinclude a source region (or a first region) and a drain region (or asecond region) that are in contact with a first electrode (for example,a source electrode) and a second electrode (for example, a drainelectrode) of each of the first to ninth transistors T1 to T9). A regionbetween the source region and the drain region may be a channel region.The channel region of the semiconductor pattern may be an intrinsicsemiconductor as a semiconductor pattern that is not doped with animpurity. The source region and the drain region may be a semiconductorpattern doped with an impurity.

Referring to FIGS. 6A and 6B, the semiconductor layer ACT may include afirst semiconductor pattern ACT1 and a second semiconductor patternACT2.

The first semiconductor pattern ACT1 may include a first dummy portionACT_DM1 and a first stem portion ACT_ST1. The first dummy portionACT_DM1 and the first stem portion ACT_ST1 may be interconnected andintegrally formed.

The first dummy portion ACT_DM1 may extend in a first direction DR1 andmay be positioned adjacent to one side of the eleventh pixel area PXA11.The first dummy portion ACT_DM1 may be connected to a reference powersource line VL_REF formed of the third conductive layer SD1 through acontact hole. Since the first dummy portion ACT_DM1 continuously extendsin the eleventh pixel area PXA11, the twelfth pixel area PXA12, and thethirteenth pixel area PXA13, the first semiconductor pattern ACT1 may beinterconnected in the first direction DR1 on the display panel 100.

The first stem portion ACT_ST1 may include a second sub-semiconductorpattern ACT_T2 and a fifth sub-semiconductor pattern ACT_T5. The secondsub-semiconductor pattern ACT_T2 may define a channel of the secondtransistor T2, and the fifth sub-semiconductor pattern ACT_T5 may definea channel of the fifth transistor T5. In an embodiment, the secondtransistor T2 may include (2_1)-th and (2_2)-th transistors T2_1 andT2_2, and the second sub-semiconductor pattern ACT_T2 may includechannel regions of the (2_1)-th and (2_2)-th transistors T2_1 and T2_2,that is, two channel regions connected in series. Similarly, the fifthtransistor T5 may include (5_1)-th and (5_2)-th transistors T5_1 andT5_2, and the fifth sub-semiconductor pattern ACT_T5 may include channelregions of the (5_1)-th and (5_2)-th transistors T5_1 and T5_2, that is,two channel regions connected in series. Each of the secondsub-semiconductor pattern ACT_T2 and the fifth sub-semiconductor patternACT_T5 may include a bent portion for forming a dual gate.

The bent portion of the second sub-semiconductor pattern ACT_T2 mayoverlap the first shielding patterns SHP1 formed of the secondconductive layer GAT2 in a third direction DR3, and thus a capacitanceis formed. The bent portion of the fifth sub-semiconductor patternACT_T5 may overlap the second shielding pattern SHP2 formed of thesecond conductive layer GAT2 in the third direction DR3, and thus acapacitance is formed. The first and second shielding patterns SHP1 andSHP2 may be connected to an anode initialization power source lineVL_aint through a contact hole, and may receive the anode initializationpower source Vaint. Accordingly, leakage current generated at thefloating node (or the bent portion) of the second transistor T2 and thefifth transistor T5 may be minimized.

According to an embodiment, as shown in FIG. 6B, a first distance d1 ofthe bent portion of the second sub-semiconductor pattern ACT_T2 in thefirst direction DR1 may be greater than a second direction d2 of thebent portion of the fifth sub-semiconductor pattern ACT_T5 in the firstdirection DR1. The bent portion of the fifth sub-semiconductor patternACT_T5 may include a first protruding expansion portion EX1 on one side.The first expansion portion EX1 may increase the area of the fifthsub-semiconductor pattern ACT_T5. Accordingly, the capacitance may beincreased at the floating node (or the bent portion) of the secondtransistor T2 and the fifth transistor T5. In general, as thecapacitance across the floating node of the transistor increases, theleakage current further decreases.

The second semiconductor pattern ACT2 may include a second dummy portionACT_DM2 and a second stem portion ACT_ST2. The second dummy portionACT_DM2 and the second stem portion ACT_ST2 may be interconnected andintegrally formed.

The second dummy portion ACT_DM2 may extend in the first direction DR1and may be positioned adjacent to another side of the eleventh pixelarea PXA11. The second dummy portion ACT_DM2 may be connected to theanode initialization power source line VL_aint formed of the thirdconductive layer SD1 through a contact hole. Since the second dummyportion ACT_DM2 continuously extends in the eleventh pixel area PXA11,the twelfth pixel area PXA12, and the thirteenth pixel area PXA13, thesecond semiconductor pattern ACT2 may be interconnected in the firstdirection DR1 on the display panel 100.

The second stem portion ACT_ST2 may include a first branch portionACT_BR1 and a second branch portion ACT_BR2. The second stem portionACT_ST2 may include an eighth sub-semiconductor pattern ACT_T8, aseventh sub-semiconductor pattern ACT_T7, a first sub-semiconductorpattern ACT_T1, and a ninth sub-semiconductor pattern ACT_T9 along acounterclockwise direction. The eighth sub-semiconductor pattern ACT_T8may constitute a channel of the eighth transistor T8, the seventhsub-semiconductor pattern ACT_T7 may constitute a channel of the seventhtransistor T7, the first sub-semiconductor pattern ACT_T1 may define achannel of the first transistor T1, and the ninth sub-semiconductorpattern ACT_T9 may define a channel of the ninth transistor T9.

According to an embodiment, the first sub-semiconductor pattern ACT_T1may include a bent portion for improving a channel capacitance.

The first branch portion ACT_BR1 may be branched between the firstsub-semiconductor pattern ACT_T1 and the seventh sub-semiconductorpattern ACT_T7 to be formed. The first branch portion ACT_BR1 mayinclude a third sub-semiconductor pattern ACT_T3 and a fourthsub-semiconductor pattern ACT_T4.

The third sub-semiconductor pattern ACT_T3 may define a channel of thethird transistor T3, and the fourth sub-semiconductor pattern ACT_T4 maydefine a channel of the fourth transistor T4. In an embodiment, thethird transistor T3 may include (3_1)-th and (3_2)-th transistors T3_1and T3_2, and the third sub-semiconductor pattern ACT_T3 may includechannel regions of the (3_1)-th and (3_2)-th transistors T3_1 and T3_2,that is, two channel regions connected in series. Similarly, the fourthtransistor T4 may include (4_1)-th and (4_2)-th transistors T4_1 andT4_2, and the fourth sub-semiconductor pattern ACT_T4 may includechannel regions of the (4_1)-th and (4_2)-th transistors T4_1 and T4_2,that is, two channel regions connected in series. Each of the thirdsub-semiconductor pattern ACT_T3 and the fourth sub-semiconductorpattern ACT_T4 may include a bent portion for forming a dual gate. Atthis time, the bent portions may overlap the third shielding patternSHP3 (shown in FIG. 6D) formed of the second conductive layer GAT2.

The respective bent portions of the third sub-semiconductor patternACT_T3 and the fourth sub-semiconductor pattern ACT_T4 may overlap thethird shielding pattern SHP3 formed of the second conductive layer GAT2in the third direction DR3, and thus a capacitance may be formed.Referring to FIGS. 6C and 6D, the third shielding pattern SHP3 may beconnected through a (1_1)-th power source line VL_VDD through a thirdbridge pattern BRP3 and may receive the first power source VDD.Accordingly, leakage current generated at the floating node (or the bentportion) of the third transistor T3 and the fourth transistor T4 may beminimized.

According to an embodiment, the bent portion of the thirdsub-semiconductor pattern ACT_T3 may include a second expansion portionEX2 on one side, and the bent portion of the fourth sub-semiconductorpattern ACT_T4 may include a third expansion portion EX3 on one side.The second expansion portion EX2 may increase the area of the thirdsub-semiconductor pattern ACT_T3, and the third expansion portion EX3may increase the area of the fourth sub-semiconductor pattern ACT_T4.Accordingly, capacitance may be increased at the floating node (or thebent portion) of the third transistor T3 and the fourth transistor T4.In general, as the capacitance across the floating node of thetransistor increases, the leakage current may further decrease.

Magnitudes of the capacitance formed at the floating node (or the bentportion) of the second transistor T2, the third transistor T3, thefourth transistor T4, and the fifth transistor T5 may be formed to besubstantially the same.

The second portion ACT_BR2 may be branched between the firstsub-semiconductor pattern ACT_T1 and the ninth sub-semiconductor patternACT_T9 and may be formed. The second branch portion ACT_BR2 may includea sixth sub-semiconductor pattern ACT_T6. The sixth sub-semiconductorpattern ACT_T6 may define a channel of the sixth transistor T6.

As described above, since each of the first semiconductor pattern ACT1and the second semiconductor pattern ACT2 is continuous in the firstdirection DR1 by the first and second dummy portions ACT_DM1 andACT_DM2, defects due to static electricity may be reduced duringmanufacture. Therefore, an increase in a yield may be expected.

Referring to FIGS. 6A to 6C, the first conductive layer GAT1 may includean eleventh capacitor electrode C1_E1, a twenty-first capacitorelectrode C2_E1, and gate patterns T2_GE, T3_GE, T4_GE, T5_GE, T6_GE,T7_GE, T8_GE, and T9_GE of the second to ninth transistors T2 to T9.

The eleventh capacitor electrode C1_E1 may have the specific area, maybe generally positioned at a center of the eleventh pixel area PXA11,and may overlap the first sub-semiconductor pattern ACTT 1. The eleventhcapacitor electrode C1_E1 may define the gate electrode of the firsttransistor T1.

The twenty-first capacitor electrode C2_E1 may have the specific areaand may be positioned above the eleventh capacitor electrode C1_E1.

The gate pattern T2_GE of the second transistor T2 may extend in thefirst direction DR1, and overlap the channel region formed in the bentportion of the second sub-semiconductor pattern ACT_T2, to definerespective gate electrodes of the (2_1)-th and (2_2)-th transistors T2_1and T2_2.

The gate pattern T3_GE of the third transistor T3 may extend in thefirst direction DR1, may be branched in a second direction DR2, and mayoverlap the channel region formed in the bent portion of the thirdsub-semiconductor pattern ACT_T3, to define respective gate electrodesof the (3_1)-th and (3_2)-th transistors T3_1 and T3_2.

The gate pattern T4_GE of the fourth transistor T4 may extend in thefirst direction DR1, may be branched in the second direction DR2, andmay overlap the channel region formed in the bent portion of the fourthsub-semiconductor pattern ACT_T4, to define respective gate electrodesof the (4_1)-th and (4_2)-th transistors T4_1 and T4_2.

The gate pattern T5_GE of the fifth transistor T5 may extend in thefirst direction DR1 and may overlap the channel region formed in thebent portion of the fifth sub-semiconductor pattern ACT_T5, to definerespective gate electrodes of the (5_1)-th and (5_2)-th transistors T5_1and T5_2.

The gate pattern T6_GE of the sixth transistor T6 may extend in thefirst direction DR1 and may overlap the channel region formed in thesixth sub-semiconductor region ACT_T2, to define a gate electrode of thesixth transistor T6.

The gate pattern T7_GE of the seventh transistor T7 may extend in thefirst direction DR1 and may overlap the channel region formed in theseventh sub-semiconductor pattern ACT_T7, to define a gate electrode ofthe seventh transistor T7.

The gate pattern T8_GE of the eighth transistor T8 and the gate patternT9_GE of the ninth transistor T9 may be integrally formed and may extendin the first direction DR1. The gate pattern T8_GE of the eighthtransistor T8 may overlap the channel region formed in the eighthsub-semiconductor pattern ACT_T8 to define a gate electrode of theeighth transistors T8, and the gate pattern T9_GE of the ninthtransistor T9 may overlap the channel region formed in the channelregion of the ninth sub-semiconductor pattern ACT_T9 to define a gateelectrode of the ninth transistors T9.

The first conductive layer GAT1 may include one or more metals selectedfrom among molybdenum (Mo), aluminum (Al), platinum (Pt), palladium(Pd), silver (Ag), magnesium (Mg), gold (Au), nickel (Ni), neodymium(Nd), iridium (Ir), chromium (Cr), titanium (Ti), tantalum (Ta),tungsten (W), and copper (Cu). The first conductive layer GAT1 may havea single-layer or multi-layer structure, and for example, the firstconductive layer GAT1 may have a single-layer structure includingmolybdenum (Mo).

Referring to FIGS. 6A to 6D, the second conductive layer GAT2 mayinclude a twelfth capacitor electrode C1_E2, the (1_1)-th power sourceline VL_VDD, and the first to third shielding patterns SHP1, SHP2, andSHP3.

The (1_1)-th power source line VL_VDD may extend in the first directionDR1, may overlap the twenty-first capacitor electrode C2_E1, and maydefine the second capacitor C2 (refer to FIG. 2A) together with thetwenty-first capacitor electrode C2_E1. The area of the (1_1)-th powersource line VL_VDD may be greater than the area of the twenty-firstcapacitor electrode C2_E1 and may cover the twenty-first capacitorelectrode C2_E1. The (1_1)-th power source line VL_VDD may include afirst opening OP1 for connecting the second bridge pattern BRP2 (shownin FIG. 6E) formed of the third conductive layer SD1 and thetwenty-first capacitor electrode C2_E1 formed of the first conductivelayer GAT1.

The twelfth capacitor electrode C1_E2 may overlap the eleventh capacitorelectrode C1_E1, and may define the first capacitor C1 (refer to FIG.2A) together with the eleventh capacitor electrode C1_E1. The area ofthe twelfth capacitor electrode C1_E2 may be greater than the area ofthe eleventh capacitor electrode C1_E1 and may cover the eleventhcapacitor electrode C1_E1. The twelfth capacitor electrode C1_E2 mayinclude a second opening OP2 for connecting the fourth bridge patternBRP4 (shown in FIG. 6E) formed of the third conductive layer SD1 and theeleventh capacitor electrode C1_E1 formed of the first conductive layerGAT1.

The first shielding pattern SHP1 may overlap the bent portion of thesecond sub-semiconductor pattern ACT_T2, and the second shieldingpattern SHP2 may overlap the bent portion of the fifth sub-semiconductorpattern ACT_T5. At this time, the first and second shielding patternsSHP1 and SHP2 may be connected to the anode initialization power sourceline VL_aint through a contact hole, and may receive the anodeinitialization power source Vaint. Accordingly, leakage current of thesecond transistor T2 and the fifth transistor T5 may be minimized.

The third shielding pattern SHP3 may overlap the bent portion of thethird and fourth sub-semiconductor regions ACT_T3 and ACT_T4. At thistime, the third shielding pattern SHP3 may be connected to the (1_1)-thpower source line VL_VDD through the third bridge pattern BRP3 and mayreceive the first power source VDD. Accordingly, leakage current of thethird transistor T3 and the fourth transistor T4 may be minimized.

The second conductive layer GAT2 may include one or more metals selectedfrom among molybdenum (Mo), aluminum (Al), platinum (Pt), palladium(Pd), silver (Ag), magnesium (Mg), gold (Au), nickel (Ni), neodymium(Nd), iridium (Ir), chromium (Cr), titanium (Ti), tantalum (Ta),tungsten (W), and copper (Cu). The second conductive layer GAT2 may havea single-layer or multi-layer structure, and for example, the secondconductive layer GAT2 may have a single-layer structure includingmolybdenum (Mo).

Referring to FIGS. 6A to 6E, the third conductive layer SD1 may includethe first to fourth scan lines SL1, SL2, SL3, SL4, the first and secondemission control lines EL1 and EL2, a (3_1)-th power source line VL_REF,a fourth power source line VL_int, a fifth power source line VL_aint, asixth power source line VL_bs, and first to fifth bridge patterns BRP1to BRP5.

The first scan line SL1 may extend in the first direction DR1. The firstscan line SL1 may be connected to the gate pattern T2_GE of the secondtransistor T2 through a contact hole.

The second scan line SL2 may extend in the first direction DR1. Thesecond scan line SL2 may be connected to the gate pattern T3_GE of thethird transistor T3 through a contact hole, and may be connected to thegate pattern T5_GE of the fifth transistor T5 through the contact hole.

The third scan line SL3 may extend in the first direction DR1. The thirdscan line SL3 may be connected to the gate pattern T4_GE of the fourthtransistor T4 through a contact hole.

The fourth scan line SL4 may extend in the first direction DR1. Thefourth scan line SL4 may be connected to the gate patterns T8_GE andT9_GE of the eighth and ninth transistors T8 and T9, which areintegrally formed, through a contact hole.

The first emission control line EL1 may extend in the first directionDR1. The first emission control line EL1 may be connected to the gatepattern T6_GE of the sixth transistor T6 through a contact hole.

The second emission control line EL2 may extend in the first directionDR1. The second emission control line EL2 may be connected to the gatepattern T7_GE of the seventh transistor T7 through a contact hole.

The (3_1)-th power source line VL_REF may extend in the first directionDR1. The (3_1)-th power source line VL_REF may be connected to oneelectrode of the fifth transistor T5 through a contact hole.

The fourth power source line VL_int may extend in the first directionDR1. The fourth power source line VL_int may be connected to oneelectrode of the fourth transistor T4 through a contact hole.

The fifth power source line VL_aint may extend in the first directionDR1. The fifth power source line VL_aint may be connected to oneelectrode of the eighth transistor T8 through a contact hole. The fifthpower source line VL_aint may be connected to the first shieldingpattern SHP1 and the second shielding pattern SHP2 through a contacthole.

The sixth power source line VL_bs may extend in the first direction DR1.The sixth power source line VL_bs may be connected to one electrode ofthe ninth transistor T9 through a contact hole.

The first bridge pattern BRP1 may overlap one electrode of the secondtransistor T2 and may be connected to one electrode of the secondtransistor T2 through a contact hole. In addition, the first bridgepattern BRP1 may be connected to the data line DL formed of the fourthconductive layer SD2 through a contact hole. That is, the first bridgepattern BRP1 may connect the one electrode of the second transistor T2and the data line DL.

The second bridge pattern BRP2 may extend in the second direction DR2and may overlap each of a portion of the first semiconductor patternACT1, the twelfth capacitor electrode C1_E2, and the twenty-firstcapacitor electrode C2_E1. The second bridge pattern BRP2 may beconnected to a portion of the first semiconductor pattern ACT1 through acontact hole, and may be connected to each of one electrode of thesecond transistor T2 and one electrode of the fifth transistor T5. Inaddition, the second bridge pattern BRP2 may be connected to the twelfthcapacitor electrode C1_E2 through a contact hole. In addition, thesecond bridge pattern BRP2 may be connected to the twenty-firstcapacitor electrode C2_E1 exposed by the first opening OP1 formed in the(1_1)-th power source line VL_VDD. That is, the second bridge patternBRP2 may define the third node N3 of FIG. 2A.

The third bridge pattern BRP3 may overlap each of the (1_1)-th powersource line VL_VDD, one electrode of the sixth transistor T6, and thethird shielding pattern SHP3. The third bridge pattern BRP3 may overlapeach of the (1_1)-th power source line VL_VDD, the one electrode of thesixth transistor T6, and the third shielding pattern SHP3 through acontact hole.

The third bridge pattern BRP3 may have an ‘H’ shape. In other words, thethird bridge pattern BRP3 may include a horizontal portion BRP3_1extending in the first direction DR1, and a first vertical portionBRP3_2 and a second vertical portion BRP3_3 disposed at both ends of thehorizontal portion BRP3_1 and extending in the second direction DR2. Atthis time, the horizontal portion BRP3_1 may overlap the twelfthcapacitor electrode C1_E2 in the third direction DR3. Each of the firstand second vertical portions BRP3_2 and BRP3_3 may be spaced apart fromthe twelfth capacitor electrode C1_E2 by a preset distance on a plane.For example, the preset distance may be about 1.5 μm.

Since the third bridge pattern BRP3 is for connecting the (1_1)-th powersource line VL_VDD to one electrode of the sixth transistor T6 and thethird shielding pattern SHP3, only the first vertical portion BRP3_2 mayperform a function. However, when the separation distance between thethird bridge pattern BRP3 (or the first vertical portion BRP3_1) and thetwelfth capacitor electrode C1_E2 is changed due to differences inmanufacturing processes, the capacitance between the third bridgepattern BRP3 (or the first vertical portion BRP3_1) and the twelfthcapacitor electrode C1_E2 may vary. The capacitance between the thirdbridge pattern BRP3 (or the first vertical portion BRP3_1) and thetwelfth capacitor electrode C1_E2 may correspond to the (2_1)-thcapacitor C2-1 (refer to FIG. 2B). Therefore, when the capacitancebetween the third bridge pattern BRP3 (or the first vertical partBRP3_1) and the twelfth capacitor electrode C1_E2 is changed, the ratioof the first capacitor C1 and the second capacitor C2 may be changed. Ingeneral, it is preferable to maintain a ratio of about 1:1 between thefirst capacitor C1 and the second capacitor C2 for a series conversionmaximum capacitance.

Therefore, the horizontal portion BRP3_1 having the predetermined areaand the twelfth capacitor electrode C1_E2 may be designed intentionallyso as to overlap in the third direction DR3, and thus the capacitanceformed between the horizontal portion BRP3_1 and the twelfth capacitorelectrode C1_E2 may be maintained. In addition, in consideration of thedifferences in manufacturing processes, each of the first and secondvertical portions BRP3_2 and BRP3_3 may be spaced apart from the twelfthcapacitor electrode C1_E2 by a preset distance when viewed in plan, andthus a capacitance may be prevented from being generated between thefirst and second vertical portions BRP3_2 and BRP3_3 and the twelfthcapacitor electrodes C1_E2.

The capacitance between the eleventh capacitor electrode C1_E1 and thetwelfth capacitor electrode C1_E2 (or the capacitance of the firstcapacitor C1) may be equal to a sum of a capacitance between thetwenty-first capacitor electrode C2_E1 and the (1_1)-th power sourceline VL_VDD (or the capacitance of the second capacitor C2) and acapacitance between the third bridge pattern BRP3 (or the first verticalportion BRP3_1) and the twelfth capacitor electrode C1_E2 (or acapacitance of the (2_1)-th capacitor C2_1). Accordingly, thecapacitance ratio of the first capacitor C1 and the second capacitor C2(including the (2_1)-th capacitor C2_1) may be substantially constantlymaintained at 1:1 regardless of differences in manufacturing processes.

In addition, each of the first and second vertical portions BRP3_2 andBRP3_3 to which the first power source VDD is supplied may shield theadjacent data line DL and first capacitor C1 (or the twelfth capacitorelectrode C1_E2), and thus crosstalk generation may be minimized.

The fourth bridge pattern BRP4 may connect one electrode of the firsttransistor T1 (or the eleventh capacitor electrode C1_E1) and oneelectrode of the third transistor T3. The fourth bridge pattern BRP4 maybe connected to the eleventh capacitor electrode C1_E1 exposed by thesecond opening OP2 formed in the twelfth capacitor electrode C1_E2. Inaddition, the fourth bridge pattern BRP4 may be connected to one regionof the third sub-semiconductor region ACT3_T3 through a contact hole.

The fifth bridge pattern BRP5 may connect one electrode of the seventhtransistor T7 and the anode of the light emitting element LD.

Referring to FIGS. 6A to 6F, the fourth conductive layer SD2 may includea sixth bridge pattern BRP6, the data line DL, a first power source lineVDDL, and a third power source line VREFL.

The sixth bridge pattern BRP6 may overlap the fifth bridge pattern BRP5and may be connected to the fifth bridge pattern BRP5 through a contacthole. The sixth bridge pattern BRP6 may be connected to one electrode ofthe seventh transistor T7 through the fifth bridge pattern BRP5. Inaddition, the sixth bridge pattern BRP6 may be connected to the anode ofthe light emitting element LD through a contact hole (not shown). Thatis, the sixth bridge pattern BRP6 may connect the one electrode of theseventh transistor T7 to the anode of the light emitting element LDtogether with the fifth bridge pattern BRP5.

The data line DL may extend in the second direction DR2, may bepositioned on a left side of the eleventh pixel area PXA11 in the firstdirection DR1, and may overlap the first bridge pattern BRP1. The dataline DL may be connected to the first bridge pattern BRP1 through acontact hole, and may be connected to one electrode of the secondtransistor T2 through the first bridge pattern BRP1.

The third power source line VREFL may extend in the second directionDR2, may be positioned on a right side of the eleventh pixel area PXA11in the first direction DR1, and may overlap the (3_1)-th power sourceline VL_REF. The third power source line VREFL may be connected to the(3_1)-th power source line VL_REF through a contact hole, and may beconnected to one electrode of the fifth transistor T5 through a contacthole.

The first power source line VDDL may extend in the second direction DR2and may be positioned between the data line DL and the third powersource line VREFL. The first power source line VDDL may be connected tothe third bridge pattern BRP3 (or an upper side of the first verticalportion BRP3_2) through a contact hole.

As described above, the first power source line VDDL may extend in thesecond direction DR2, and the (1_1)-th power source line VL_VDDconnected to the first power source line VDDL through the third bridgepattern BRP3 and a contact hole may extend in the first direction DR1and thus may have a mesh structure. In addition, the third power sourceline VREFL may extend in the second direction DR2, and the (3_1)-thpower source line VL_REF connected to the third power source line VREFLthrough a contact hole may extend in the first direction DR1 and thusmay have a mesh structure. Accordingly, IR drop may be reduced, andstain distribution of the display panel 100 may be reduced.

The third conductive layer SD1 and the fourth conductive layer SD2 mayinclude one or more metals selected from among molybdenum (Mo), aluminum(Al), platinum (Pt), palladium (Pd), silver (Ag), magnesium (Mg), gold(Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), titanium(Ti), tantalum (Ta), tungsten (W), and copper (Cu). The third conductivelayer SD1 and the fourth conductive layer SD2 may have a single-layer ormulti-layer structure, and for example, the third conductive layer SD1and the fourth conductive layer SD2 may have a multi-layer structure ofTi/AL/Ti.

FIG. 7 is a partial cross-sectional view of a portion of the pixels ofFIG. 6A. FIGS. 8 to 10C are enlarged cross-sectional views ofembodiments of an emission layer of a display device constructedaccording to the principles of the invention.

Referring to FIGS. 2A, 6A, and 7 , since the eleventh to thirteenthpixels PX11 to PX13 (or light emitting units of the eleventh tothirteenth pixels PX11 to PX13) are substantially the same as or similarto each other, hereinafter, the description of eleventh pixel PX11 isapplicable to each of the eleventh to thirteenth pixels PX11 to PX13.

In FIG. 7 , one pixel is shown in a simplified manner, such as showingan electrode as an electrode of a single layer and a plurality ofinsulating layers as only an insulating layer of a single layer, but theembodiments are not limited thereto.

In addition, in an embodiment, unless otherwise specified, “formedand/or provided on the same layer” may mean formed in the same process,and “formed and/or provided on different layers” may mean formed indifferent processes.

A pixel circuit layer PCL, a display element layer DPL, and a thin filmencapsulation layer TFE may be sequentially disposed on a base layer SUB(or substrate).

The pixel circuit layer PCL may include a buffer layer BFL, asemiconductor layer ACT, a first insulating layer GI1 (or a first gateinsulating layer), the first conductive layer GAT1, a second insulatinglayer GI2 (or a second gate insulating layer), the second conductivelayer GAT2, a third insulating layer ILD (or an interlayer insulatinglayer), the third conductive layer SD1, a first protective layer PSV1 (afirst via layer, or a fourth insulating layer), the fourth conductivelayer SD2, and a second protective layer PSV2 (a second via layer, or afifth insulating layer).

The buffer layer BFL, the semiconductor layer ACT, the first insulatinglayer GI1, the first conductive layer GAT1, the second insulating layerGI2, the second conductive layer GAT2, the third insulating layer ILD,the third conductive layer SD1, the first protective layer PSV1, thefourth conductive layer SD2, and the second protective layer PSV2 may besequentially stacked on the base layer SUB. Since the semiconductorlayer ACT, the first conductive layer GAT1, the second conductive layerGAT2, the third conductive layer SD1, and the fourth conductive layerSD2 are described with reference to FIG. 6A, a repetitive description isomitted.

The base layer SUB may be formed of an insulating material such as glassor resin. In addition, the base layer SUB may be formed of a materialhaving flexibility to be bent or folded, and may have a single-layerstructure or a multi-layer structure. For example, the material havingflexibility may include at least one among polystyrene, polyvinylalcohol, polymethyl methacrylate, polyethersulfone, polyacrylate,polyetherimide, polyethylene naphthalate, polyethylene terephthalate,polyphenylene sulfide, polyarylate, polyimide, polycarbonate, triacetatecellulose, and cellulose acetate propionate. However, the materialconfiguring the base layer SUB is not limited to the above-describedembodiments.

The buffer layer BFL may be disposed on the entire surface of the baselayer SUB. The buffer layer BFL may prevent diffusion of an impurity ionand may prevent penetration of moisture or external air. The bufferlayer BFL may be an inorganic insulating layer including an inorganicmaterial. The inorganic insulating layer may include, for example, atleast one of a metal oxide such as silicon nitride (SiNx), silicon oxide(SiOx), silicon oxynitride (SiON), and aluminum oxide (AlOx). The bufferlayer BFL may be provided as a single layer, or may be provided as amultilayer of at least a double layer. When the buffer layer BFL isprovided as a multilayer, each layer may be formed of the same materialor different materials. The buffer layer BFL may be omitted according tothe material and a process condition of the base layer SUB.

The semiconductor layer ACT may be disposed on the buffer layer BFL. Thesemiconductor layer ACT may be disposed between the buffer layer BFL andthe first insulating layer GI1. The semiconductor layer ACT may includethe seventh sub-semiconductor pattern ACT_T7 configuring the seventhtransistor T7. The seventh sub-semiconductor pattern ACT_T7 may includea first region contacting a first transistor electrode ET1, a secondregion contacting a second transistor electrode ET2, and a channelregion positioned between the first and second regions. The seventhsub-semiconductor pattern ACT_T7 of the seventh transistor T7 may be asemiconductor pattern formed of amorphous silicon, polysilicon,low-temperature polysilicon, or the like. However, the embodiments arenot limited thereto, and the seventh sub-semiconductor pattern ACT_T7 ofthe seventh transistor T7 may be a semiconductor pattern including anoxide semiconductor. The channel region may be, for example, asemiconductor pattern that is not doped with an impurity, and may be anintrinsic semiconductor. The first region and the second region may besemiconductor patterns doped with impurities.

The first insulating layer GI1 may be disposed on the semiconductorlayer ACT. The first insulating layer GI1 may be an inorganic insulatinglayer including an inorganic material. For example, the first insulatinglayer GI1 may include the same material as the buffer layer BFL, or mayinclude one or more materials selected from the materials exemplified asthe configuration material of the buffer layer BFL. According to anembodiment, the first insulating layer GI1 may be formed of an organicinsulating layer including an organic material. The first insulatinglayer GI1 may be provided as a single layer, but may be provided as amultilayer of at least a double layer.

The first conductive layer GAT1 may be disposed on the first insulatinglayer GI1. As described with reference to FIG. 6A, the first conductivelayer GAT1 may include the gate pattern T7_GE of the seventh transistorT7, the eleventh capacitor electrode C1_E11, and the twenty-firstcapacitor electrode C2_E21.

The second insulating layer GI2 may be disposed on the first insulatinglayer GI1 and the first conductive layer GAT1. The second insulatinglayer GI2 may be generally disposed over the entire surface of the baselayer SUB. The second insulating layer GI2 may include the same materialas the first insulating layer GI1 or may include one or more materialsselected from the materials exemplified as the configuration material ofthe first insulating layer GI1.

The second conductive layer GAT2 may be disposed on the secondinsulating layer GI2. As described with reference to FIG. 6A, the secondconductive layer GAT2 may include the twelfth capacitor electrode C1_E12and the (1_1)-th power source line VL_VDD. The twelfth capacitorelectrode C1_E12 may overlap the eleventh capacitor electrode C1_E11,and may define the first capacitor C1 together with the eleventhcapacitor electrode C1_E11. The (1_1)-th power source line VL_VDD mayoverlap the twenty-first capacitor electrode C2_E21, and may define thesecond capacitor C2 together with the twenty-first capacitor electrodeC2_E21. The (1_1)-th power source line VL_VDD may include the firstopening OP1.

The third insulating layer ILD may be disposed on the second insulatinglayer GI2 and the second conductive layer GAT2. The third insulatinglayer ILD may be generally disposed over substantially the entiresurface of the base layer SUB.

The third insulating layer ILD may include an inorganic insulatingmaterial such as a silicon compound or a metal oxide. For example, thefirst insulating layer GI1 may include silicon oxide, silicon nitride,silicon oxynitride, aluminum oxide, tantalum oxide, hafnium oxide,zirconium oxide, titanium oxide, or a combination thereof. The thirdinsulating layer ILD may be a single layer or a multilayer formed of astack layer of different materials.

The third conductive layer SD1 may be disposed on the third insulatinglayer ILD. As described with reference to FIG. 6A, the third conductivelayer SD1 may include the second bridge pattern BRP2, the fifth bridgepattern BRP5, and the fifth power source line VL_aint.

The fifth power source line VL_aint may overlap one region of theseventh sub-semiconductor pattern ACT_T7, may be connected to one regionof the seventh sub-semiconductor pattern ACT_T7 through a contact holepassing through the first insulating layer GI1, the second insulatinglayer GI2, and the third insulating layer ILD, and may define the firsttransistor electrode ET1 of the seventh transistor T7.

The fifth bridge pattern BRP5 may overlap another region of the seventhsub-semiconductor pattern ACT_T7, may be connected to another region ofthe seventh sub-semiconductor pattern ACT_T7 through a contact holepassing through the first insulating layer GI1, the second insulatinglayer GI2, and the third insulating layer ILD, and may define the secondtransistor electrode ET2 of the seventh transistor T7.

The second bridge pattern BRP2 may be connected to the twelfth capacitorelectrode C1_E12 through a contact hole. The second bridge pattern BRP2may be connected to the twenty-first capacitor electrode C2_E21 througha contact hole formed in the first opening OP1. The second bridgepattern BRP2 may define the third node N3 of FIG. 2A.

The first protective layer PSV1 may be disposed on the third insulatinglayer ILD and the third conductive layer SD1. The first protective layerPSV1 may be generally disposed over the entire surface of the base layerSUB.

The first protective layer PSV1 may include an organic insulatingmaterial such as polyacrylates resin, epoxy resin, phenolic resin,polyamides resin, polyimides rein, unsaturated polyester resin,polyphenyleneethers resin, polyphenylenesulfides resin, orbenzocyclobutene (BCB).

The fourth conductive layer SD2 may be disposed on the first protectivelayer PSV1. As described with reference to FIG. 6A, the fourthconductive layer SD2 may include the sixth bridge pattern BRP6, thefirst power source line VDDL, and the third power source line VREFL.

The sixth bridge pattern BRP6 may overlap the fifth bridge pattern BRP5and may be connected to the fifth bridge pattern BRP5 through a contacthole CNT_1 passing through the first protective layer PSV1.

The third power source line VREFL may overlap a partial region of thefifth power source line VL_aint.

The first power source line VDDL may overlap the first capacitor C1 andthe second capacitor C2.

The second protective layer PSV2 may be disposed on the first protectivelayer PSV1 and the fourth conductive layer SD2. The second protectivelayer PSV2 may be generally disposed over the entire surface of the baselayer SUB. The second protective layer PSV2 may include the samematerial as the first protective layer PSV1 or may include one or morematerials selected from the materials exemplified as the configurationmaterial of the first protective layer PSV1.

The display element layer DPL may be provided on the second protectivelayer PSV2.

The display element layer DPL may include an anode AD, a pixel defininglayer PDL, an emission layer EML, and a cathode CD. The anode AD, thepixel defining layer PDL, the emission layer EML, and the cathode CD maybe sequentially disposed or formed on the second protective layer PSV2(or the pixel circuit layer PCL).

The anode AD may be disposed on the second protective layer PSV2. Theanode AD may correspond to an emission area EA of each pixel.

The anode AD may be connected to the sixth bridge pattern BRP6 through acontact hole CNT_2 passing through the second protective layer PSV2 andexposing the sixth bridge pattern BRP6. The anode AD may be connected tothe second transistor electrode ET2 of the seventh transistor T7 throughthe sixth bridge pattern BRP6 and the fifth bridge pattern BRP5.

The anode AD may be formed of a conductive material (or substance)having a substantially constant reflectance. The conductive material (orsubstance) may include an opaque metal. The opaque metal may include,for example, a metal such as silver (Ag), magnesium (Mg), aluminum (Al),platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), neodymium (Nd),iridium (Jr), chromium (Cr), titanium (Ti), molybdenum (Mo), and analloy thereof. According to an embodiment, the anode AD may include atransparent conductive material (or substance). The transparentconductive material (or substance) may include a conductive oxide suchas indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO),indium gallium zinc oxide, IGZO), or indium tin zinc oxide (ITZO), and aconductive polymer such as poly(3,4-ethylenedioxythiophene) (PEDOT).

The pixel defining layer PDL may be disposed or formed on the secondprotective layer PSV2 and the anode AD in a non-emission area NEA. Thepixel defining layer PDL may partially overlap an edge of the anode ADin the non-emission area NEA. The pixel defining layer PDL may includean insulating material including an inorganic material and/or an organicmaterial. For example, the pixel defining layer PDL may include aninorganic layer of at least one layer including various currently knowninorganic insulating materials including silicon nitride (SiNx) orsilicon oxide (SiOx). Alternatively, the pixel defining layer PDL mayinclude an organic layer, a photoresist layer, and/or the like of atleast one layer including various currently known organic insulatingmaterials, or may be defined as an insulator of a single layer ormultiple layers by including organic/inorganic materials in combination.That is, the configuration material of the pixel defining layer PDL maybe variously changed.

In an embodiment, the pixel defining layer PDL may include at least onelight blocking material and/or a reflective material to prevent a lightleakage defect in which light (or rays) leaks between pixels. Accordingto an embodiment, the pixel defining layer PDL may include a transparentmaterial (or substance). The transparent material may include, forexample, polyamides resin, polyimides resin, and the like, but theembodiments are not limited thereto. According to another embodiment, areflective material layer may be separately provided and/or formed onthe pixel defining layer PDL to further improve efficiency of lightemitted from each pixel.

The emission layer EML may be disposed on the anode AD in the emissionarea EA. That is, the emission layer EML may be formed separately ineach of the plurality of pixels PX. The emission layer EML may includean organic material and/or an inorganic material to emit light of apredetermined color. For example, the pixel PX may include first tothird sub-pixels. Each of the first to third sub-pixels may emit redlight, green light, and blue light. However, the embodiments are notlimited thereto, and for example, the emission layer EML may be commonlydisposed in the plurality of pixels PX. At this time, the emission layerEML may emit white light.

The emission layer EML may have a single emission structure, a two-stacktandem emission structure, and a three-stack tandem emission structure.Hereinafter, it is assumed that an emission structure of FIGS. 8 to 10is identically applied to all pixels PXL included in the display panel100. That is, all pixels PXL included in the display panel 100 may emitlight of substantially the same color. In this case, a color filter maybe further included on the display element layer DPL shown in FIG. 7 .The color filter may include a color filter material that selectivelytransmits light of a specific color converted by color changingparticles. When the pixel is a red pixel, the color filter may include ared color filter. In addition, when the pixel is a green pixel, thecolor filter may include a green color filter. In addition, when thepixel is a blue pixel, the color filter may include a blue color filter.

Referring to FIGS. 7 and 8 , the single emission structure may includethe emission layer EML, an electron transport region ETR, and a holetransport region HTR. The emission layer EML may be disposed between theelectron transport region ETR and the hole transport region HTR.According to an embodiment, the electron transport region ETR may beelectrically connected to the cathode CD of the light emitting elementLD, and the hole transport region ETR may be electrically connected tothe anode AD of the light emitting element LD.

Referring to FIGS. 7 and 9 , a two-stack tandem emission structureaccording to an embodiment may include a plurality of emission structureunits. For example, the two-stack tandem emission structure may includea first emission structure unit EU1 adjacent to the anode AD of thelight emitting element LD and a second emission structure unit EU2adjacent to the cathode CD.

Each of the first and second emission structure units EU1 and EU2includes an emission layer that generates light according to an appliedcurrent. For example, the first emission structure unit EU1 may includea first emission layer EML1, a first electron transport region ETR1, anda first hole transport region HTR1. The first emission layer EML1 may bedisposed between the first electron transport region ETR1 and the firsthole transport region HTR1. For example, the second emission structureunit EU2 may include a second emission layer EML2, a second electrontransport region ETR2, and a second hole transport region HTR2. Thesecond emission layer EML2 may be disposed between the second electrontransport region ETR2 and the second hole transport region HTR2.

Each of the first hole transport region HTR1 and the second holetransport region HTR2 may include at least one of a hole injection layerand a hole transport layer, and may further include a hole buffer layer,an electron blocking layer, and the like as necessary. The first holetransport region HTR1 and the second hole transport region HTR2 may havethe same configuration or different configurations.

Each of the first electron transport region ETR1 and the second electrontransport region ETR2 may include at least one of an electron injectionlayer and an electron transport layer, and may further include anelectron buffer layer, a hole blocking layer, and the like as necessary.The first electron transport region ETR1 and the second electrontransport region ETR2 may have the same configuration or differentconfigurations.

A connection layer CGL may be disposed between the first emissionstructure unit EU1 and the second emission structure unit EU2.

For example, the connection layer CGL may have a stack structure of a pdopant layer and an n dopant layer. For example, the p dopant layer mayinclude a p-type dopant such as HAT-CN, TCNQ, and NDP-9, and the ndopant layer may include an alkali metal, an alkaline earth metal, alanthanide-based metal, or a combination thereof. According to anembodiment, the first emission layer EML1 and the second emission layerEML2 may generate light of the same color.

According to an embodiment, the first emission layer EML1 may generatelight of a color different from that of the second emission layer EML2.According to an embodiment, the light emitted from each of the firstemission layer EML1 and the second emission layer EML2 may be mixed togenerate white light. For example, the first emission layer EML1 maygenerate blue light, and the second emission layer EML2 may generateyellow light.

The cathode CD may be disposed on the emission layer EML. The cathode CDmay be commonly disposed in the plurality of pixels PX.

The thin film encapsulation layer TFE may be disposed on the cathode CD.The thin film encapsulation layer TFE may be commonly disposed in theplurality of pixels PX. In FIG. 7 , the thin film encapsulation layerTFE directly covers the cathode CD, but a capping layer CPL (refer toFIG. 11 ) covering the cathode CD may be further disposed between thethin film encapsulation layer TFE and the cathode CD.

Referring to FIGS. 7 and 10A, the three-stack tandem emission structuremay include three or more emission structure units.

For example, as shown in FIG. 10A, the three-stack tandem emissionstructure may include a first emission structure unit EU1, a secondemission structure unit EU2, and a third emission structure unit EU3.

The three-stack tandem emission structure includes an emission layerthat each generate light according to an applied current. For example,the first emission structure unit EU1 may include a first emission layerEML1, a first electron transport region ETR1, and a first hole transportregion HTR1. The first emission layer EML1 may be disposed between thefirst electron transport region ETR1 and the first hole transport regionHTR1. The second emission structure unit EU2 may include a secondemission layer EML2, a second electron transport region ETR2, and asecond hole transport region HTR2. The second emission layer EML2 may bedisposed between the second electron transport region ETR2 and thesecond hole transport region HTR2. The third emission structure unit EU3may include a third emission layer EML3, a third electron transportregion ETR3, and a third hole transport region HTR3. The third emissionlayer EML3 may be disposed between the third electron transport regionETR3 and the third hole transport region HTR3.

Each of the first hole transport region HTR1, the second hole transportregion HTR2, and the third hole transport region HTR3 may include atleast one of a hole injection layer and a hole transport layer, and mayfurther include a hole buffer layer, an electron blocking layer, and thelike as necessary. The first hole transport region HTR1, the second holetransport region HTR2, and the third hole transport region HTR3 may havethe same configuration or different configurations.

Each of the first electron transport region ETR1, the second electrontransport region ETR2, and the third electron transport region ETR3 mayinclude at least one of an electron injection layer and an electrontransport layer, and may further include an electron buffer layer, ahole blocking layer, and the like as necessary. The first electrontransport region ETR1, the second electron transport region ETR2, andthe third electron transport region ETR3 may have the same configurationor different configurations.

A first connection layer CGL1 may be disposed between the first emissionstructure unit EU1 and the second emission structure unit EU2. A secondconnection layer CGL2 may be disposed between the second emissionstructure unit EU2 and the third emission structure unit EU3.

According to an embodiment, the first emission layer EML1 and the thirdemission layer EML3 may generate light of a color different from that oflight of the second emission layer EML2. According to an embodiment, thelight emitted from each of the first to third emission layers EML1 toEML3 may be mixed to generate white light. For example, the firstemission layer EML1 and the third emission layer EML3 may generate bluelight, and the second emission layer EML2 may generate yellow light.

However, the embodiments are not limited thereto, and the secondemission layer EML2 may further include sub-emission layers EML2′ andEML2″ to improve purity. For example, as shown in FIG. 10B, the secondemission layer EML2 may include a (2-1)-th sub-emission layer EML2′disposed at a lower portion. At this time, the (2-1)-th sub-emissionlayer EML2′ may generate red light. In addition, as shown in FIG. 10C,the second emission layer EML2 may include a (2-1)-th sub-emission layerEML2′ disposed at a lower portion and a (2-2)-th sub-emission layerEML2″ disposed at an upper portion. At this time, the (2-1)-thsub-emission layer EML2′ may generate red light, and the (2-2)-thsub-emission layer EML2″ may generate green light.

The single emission structure, the two-stack tandem emission structure,and the three-stack tandem emission structure may be formed by vacuumdeposition, inkjet printing, or the like.

FIG. 11 is a schematic diagram of an embodiment of a two-stack tandememission structure of the emission layer constructed according to theprinciples of the invention. At this time, FIG. 11 is a schematiccross-sectional view of one unit pixel shown in FIG. 6A, that is, theeleventh pixel PX11, the twelfth pixel PX12, and the thirteenth pixelPX13. Hereinafter, for convenience of description, the embodiment isdescribed under premise that the eleventh pixel PX11 includes a redemission layer R, the twelfth pixel PX12 includes a green emission layerG, and the thirteenth pixel PX13 includes a blue emission layer B.

Referring to FIG. 11 , a two-stack tandem emission structure accordingto another embodiment may include a plurality of emission structureunits. For example, the two-stack tandem emission structure may includea first emission structure unit EU1 adjacent to the anode AD of thelight emitting element LD and a second emission structure unit EU2adjacent to the cathode CD.

Each of the first and second emission structure units EU1 and EU2includes an emission layer that generates light according to an appliedcurrent. For example, the first emission structure unit EU1 may includea first emission layer EML1, a first electron transport region ETR1, anda first hole transport region HTR1. The first emission layer EML1 may bedisposed between the first electron transport region ETR1 and the firsthole transport region HTR1. For example, the second emission structureunit EU2 may include a second emission layer EML2, a second electrontransport region ETR2, and a second hole transport region HTR2. Thesecond emission layer EML2 may be disposed between the second electrontransport region ETR2 and the second hole transport region HTR2.

Each of the first hole transport region HTR1 and the second holetransport region HTR2 may include at least one of a hole injection layerand a hole transport layer, and may further include a hole buffer layer,an electron blocking layer, and the like as necessary. The first holetransport region HTR1 and the second hole transport region HTR2 may havethe same configuration or different configurations.

Each of the first electron transport region ETR1 and the second electrontransport region ETR2 may include at least one of an electron injectionlayer and an electron transport layer, and may further include anelectron buffer layer, a hole blocking layer, and the like as necessary.The first electron transport region ETR1 and the second electrontransport region ETR2 may have the same configuration or differentconfigurations.

A connection layer CGL may be disposed between the first emissionstructure unit EU1 and the second emission structure unit EU2.

For example, the connection layer CGL may have a stack-structure of a pdopant layer and an n dopant layer. For example, the p dopant layer mayinclude a p-type dopant such as HAT-CN, TCNQ, and NDP-9, and the ndopant layer may include an alkali metal, an alkaline earth metal, alanthanide-based metal, or a combination thereof. According to anembodiment, the first emission layer EML1 and the second emission layerEML2 may generate light of the same color.

In the eleventh pixel PX11, the twelfth pixel PX12, and the thirteenthpixel PX13 shown in FIG. 11 , the anode AD, an emission auxiliary layerR′, the red emission layer R, the green emission layer G, and the blueemission layer B may be formed separately for each of the eleventh pixelPX11, the twelfth pixel PX12, and the thirteenth pixel PX13, and thefirst electron transport region ETR1, the second electron transportregion ETR2, the first hole transport region HTR1, the second holetransport region HTR2, the connection layer CGL, and the cathode CD maybe commonly stacked with respect to the eleventh pixel PX11, the twelfthpixel PX12, and the thirteenth pixel PX13.

A reflective layer RFL may be included between the anode AD and thefirst hole transport region HTR1. The reflective layer RFL may be atransparent conductive layer. The transparent conductive layer mayinclude a transparent conductive oxide (TCO), and may include at leastone of indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide(ZnO), aluminum zinc oxide (AZO), and indium oxide (In2O3). Thetransparent conductive layer has a relatively high work function. Whenthe anode AD includes a transparent conductive layer, hole injectionthrough the anode AD may be facilitated.

The cathode CD may be formed of a semi-transmissive layer including ametal. A capping layer CPL covering the cathode CD may be furtherdisposed on the cathode CD. The capping layer CPL may serve to protectthe emission layers EML1 and EML2 and to help light generated from theemission layers EML1 and EML2 to be efficiently emitted to outside ofthe panel. A buffer layer and a metal layer may be further includedbetween the second emission layer EML2 and the cathode CD.

A fine resonance structure may be applied to the first emission layerEML1 and the second emission layer EML2 so that the light generated fromthe first emission layer EML1 and the second emission layer EML2 may beeffectively emitted to outside of the panel. When light is repeatedlyreflected between the anode AD including the reflective layer RFL andthe cathode CD which is the semi-transmissive layer, light of a specificwavelength corresponding to a reflection distance may be amplified,light of other wavelengths may be canceled, the amplified light may beemitted to outside of the panel through the cathode CD which is thesemi-transmissive layer.

The emission auxiliary layer R′ may include a hole transport material,and the emission auxiliary layer R′ may be formed of the same materialas the hole transport regions HTR1 and HTR2. For example, the emissionauxiliary layer R′ may include one or more among hole transportmaterials selected from a group consisting of NPD (N, N-dinaphthyl-N,N′-diphenyl benzidine), TPD (N, N′-bis-(3-methylphenyl)-N, N′-bis(phenyl)-benzidine), s-TAD, and MTDATA (4, 4′,4″-Tris(N-3-methylphenyl-Nphenyl-amino)-triphenylamine). The emissionauxiliary layer R′ may serve to transport a hole to the red emissionlayer R and serve to adjust a thickness of the second emission structureunit EU2 (that is, the second hole transport region HTR2, the emissionauxiliary layer R′, the red emission layer R, and the second electrontransport region ETR2).

According to an embodiment, the emission auxiliary layer R′ may beformed only in the eleventh pixel PX11. That is, the eleventh pixel PX11may include the emission auxiliary layer R′ and the red emission layer Rsequentially stacked in the second emission layer EML2, the twelfthpixel PX12 may include only the green emission layer G in the secondemission layer EML2, and the thirteenth pixel PX13 may include only theblue emission layer B in the second emission layer EML2.

As shown in FIG. 11 , the eleventh pixel PX11 may be designed to causesecond resonance is generated between the reflective layer RFL of theanode AD and the cathode CD by including a structure in which theemission auxiliary layer R′ and the red emission layer R aresequentially stacked in the second emission layer EML2, and each of thetwelfth pixel PX12 and the thirteenth pixel PX13 may be designed tocause first resonance is generated between the reflective layer RFL ofthe anode AD and the cathode CD by including only the green emissionlayer G and the blue emission layer B in the second emission layer EML2.At this time, transmittance of the light emitted from the emissionlayers EML1 and EML2 varies according to a distance t between thereflective layer RFL of the anode AD and the cathode CD, the lighttransmittance may be increased as the distance t is decreased. That is,the light transmittance at the time of the first resonance may begreater than the light transmittance at the time of the secondresonance. In FIG. 11 , the thickness of the second emission layer EML2is the same for convenience of description, but as described above, thehole transport regions HTR1 and HTR2, the electron transport regionsETR1 and ETR2, the connection layer CGL, and the cathode CD are stackedcommonly with respect to the eleventh pixel PX11, the twelfth pixelPX12, and the thirteenth pixel PX13, and thus it should be understoodthat the thickness of the second emission layer EML2 is decreased in anorder of the eleventh pixel PX11, the twelfth pixel PX12, and thethirteenth pixel PX13.

Although certain embodiments and implementations have been describedherein, other embodiments and modifications will be apparent from thisdescription. Accordingly, the inventive concepts are not limited to suchembodiments, but rather to the broader scope of the appended claims andvarious obvious modifications and equivalent arrangements as would beapparent to a person of ordinary skill in the art.

What is claimed is:
 1. A pixel of a display device, the pixelcomprising: a light emitting element; a first transistor coupled betweena first voltage and a second node and having a gate electrode connectedto a first node; a first capacitor including one electrode connected tothe first node and another electrode connected to a third node; a secondtransistor coupled between the third node and a data line; a thirdtransistor coupled between the first node and the second node; a fifthtransistor coupled between a second voltage and the third node; and aneighth transistor coupled between a fourth node and a third voltage. 2.The pixel according to claim 1, further comprising: a fourth transistorcoupled between the first node and a fourth voltage.
 3. The pixelaccording to claim 2, further comprising: a sixth transistor coupledbetween the first voltage and a fifth node connected to one electrode ofthe first transistor; and a seventh transistor coupled between thesecond node and the fourth node.
 4. The pixel according to claim 3,further comprising: a ninth transistor coupled between the fifth nodeand a fifth voltage.
 5. The pixel according to claim 1, furthercomprising: a second capacitor including one electrode connected to thefirst voltage and another electrode connected to the third node.
 6. Thepixel according to claim 1, wherein the second transistor has a gateelectrode connected to a first signal.
 7. The pixel according to claim1, wherein the third transistor has a gate electrode connected to asecond signal.
 8. The pixel according to claim 2, wherein the fourthtransistor has a gate electrode connected to a third signal.
 9. Thepixel according to claim 1, wherein the fifth transistor has a gateelectrode connected to the second signal.
 10. The pixel according toclaim 3, wherein the sixth transistor has a gate electrode connected toa fourth signal.
 11. The pixel according to claim 3, wherein the seventhtransistor has a gate electrode connected to a fifth signal.
 12. Thepixel according to claim 1, wherein the eighth transistor has a gateelectrode connected to a sixth signal.
 13. The pixel according to claim4, wherein the ninth transistor has a gate electrode connected to thesixth signal.
 14. The pixel according to claim 1, wherein the firsttransistor is configured to control a driving current supplied to thelight emitting element in response to a voltage of the first node. 15.The pixel according to claim 4, wherein at least one of the first toninth transistors includes an oxide semiconductor.
 16. The pixelaccording to claim 1, further comprising at least one power supply tosupply one or more of the first voltage, the second voltage, the thirdvoltage and the fourth voltage.